question_answer 1)
If the momentum of electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 2)
Which of the following figures represents the variation of particle momentum and the associated de-Broglie wavelength?
A)
B)
C)
D)
View Solution play_arrow
question_answer 3)
Electrons are accelerated through a potential difference V and protons are accelerated through a potential difference 4 V. The de-Broglie wavelengths are \[{{\lambda }_{e}}\] and \[{{\lambda }_{p}}\] for electrons and protons respectively. The ratio of \[\frac{{{\lambda }_{e}}}{{{\lambda }_{p}}}\]is given by: (given \[{{m}_{e}}\]is mass of electron and \[{{m}_{p}}\]is mass of proton)
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 4)
An electron of mass 'm' and charge 'e' initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t, ignoring relativistic effects is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 5)
A proton and a deuteron are accelerated through the same accelerating potential. Which one of the two has greater value of de-Broglie wavelength associated with it, and less momentum?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 6)
A particle of mass M at rest decays into two particles of masses \[{{m}_{1}}\] and \[{{m}_{2}}\] having non-zero velocities. The ratio of the de Broglie wavelengths of the particles, \[{{\lambda }_{1}}/{{\lambda }_{2}},\] is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 7)
A light of wavelength \[\lambda \] and intensity l is incident normally on the surface. If reflection coefficient of surface is r, the pressure exerted by light on the surface is equal to
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 8)
An electron microscope uses electrons accelerated by a voltage of 50 kV. If \[\lambda \] be the de-Broglie wavelength associated with the electrons. Also taking other factors, such as numerical aperture etc. to be same, the resolving power of an electron microscope be Re & that of an optical microscope which used yellow light is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 9)
A proton has kinetic energy E = 100 keV which is equal to that of a photon. The wavelength of photon is \[{{\lambda }_{2}}\] and that of proton is \[{{\lambda }_{1}}.\] The ration of \[{{\lambda }_{2}}/{{\lambda }_{1}}\] is proportional to
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 10)
Electrons with de-Broglie wavelength X fall on the target in an X-ray tube. The cut-off wavelength of the emitted X-rays is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 11)
The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (Kelvin) and mass m, is:-
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 12)
A homogeneous ball (mass = m) of ideal black material at rest is illuminated with a radiation having a set of photons (wavelength = X), each with the same momentum and the same energy. The rate at which photons fall on the ball is n. The linear acceleration of the ball is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 13)
A particle of mass m is projected from ground with velocity u making angle \[\theta \] with the vertical. The de-Broglie wavelength of the particle at the highest point is -
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 14)
An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 15)
An electron is accelerated through a potential difference of V volt. It has a wavelength associated with them is.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 16)
Assume that the de Broglie wave associated with an electron can form a standing wave between the atoms arranged in a one dimensional array with nodes at each of the atomic sites. It is found that one such standing wave is formed if the distance d between the atoms of the array is \[2\overset{\text{o}}{\mathop{\text{A}}}\,\]A similar standing wave is again formed if d is increased to \[2.5\overset{\text{o}}{\mathop{\text{A}}}\,\]but not for any intermediate value of d. The energy of the electrons in electron volt and the least value of d for which the standing wave of the type described above can form, respectively are
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 17)
When a beam of 10.6 eV photons of intensity \[2.0\text{ }W/{{m}^{2}}\,\] falls on a platinum surface of area \[1.0\times {{10}^{-4}}{{m}^{2}}\] and work function 5.6 eV, 0.53% of the incident photons eject photoelectrons, then the number of photoelectrons emitted per second and their minimum & maximum energies (in eV) [Take \[1eV=1.6\times {{10}^{-19}}J\]] are respectively.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 18)
When a surface is irradiated with light of wavelength \[4950\overset{\text{o}}{\mathop{\text{A}}}\,\], a photocurrent appears which vanishes if a retarding potential greater than 0.6 V is applied across the photo tube. When a different source of light is used, it is found that the critical retarding potential is changed to 1.1 V. Find the wavelength of second source.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 19)
Find the frequency of light which ejects electrons from a metal surface fully stopped by a retarding potential of 3V. The photoelectric effect begin in this metal at frequency of \[6\times {{10}^{14}}\] per second.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 20)
The potential energy of a particle of mass m is given by \[V\left( x \right)=\left\{ \begin{matrix} {{E}_{0}}; & 0\le x\le 1 \\ 0; & x>1 \\ \end{matrix} \right\}\]\[{{\lambda }_{1}}\] and \[{{\lambda }_{2}}\]are the de-Broglie wavelengths of the particle, when \[0\le x\le 1\] and \[x>1\]respectively. If the total energy of particle is\[2{{E}_{0}}\], find \[{{\lambda }_{1}}/{{\lambda }_{2}}\].
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 21)
Light of wavelength 180 nm ejects photoelectron from a plate of a metal whose work function is 2 eV. If a uniform magnetic field of \[5\times {{10}^{-5}}T\] is applied parallel to plate, what would be the radius of the path followed by electrons ejected normally from the plate with maximum energy?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 22)
A cylindrical rod of some laser material \[5\times {{10}^{-2}}m\] long and \[{{10}^{-2}}\] m in diameter contains \[2\times {{10}^{25}}\] ions \[6.6\times {{10}^{-7}}m.\] per m3. If on excitation all the ions are in the upper energy level and de-excite simultaneously emitting photons in the same direction, calculate the maximum energy contained in a pulse of radiation of wavelength \[6.6\times {{10}^{-7}}m.\] If the pulse lasts for\[{{10}^{-7}}s\]. the average power of the laser during the pulse is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 23)
Radiation of wavelength \[\lambda \], is incident on a photocell. The fastest emitted electron has speed v. If the wavelength is changed to \[\frac{3\lambda }{4}\], the speed of the fastest emitted electron will be:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 24)
An electron beam is accelerated by a potential difference V to hit a metallic target to produce X- rays. It produces continuous as well as characteristic X-rays. If \[{{\lambda }_{\min }}\] is the smallest possible wavelength of X-ray in the spectrum, the variation of log \[{{\lambda }_{\min }}\] with log V is correctly represented in:
A)
B)
C)
D)
View Solution play_arrow
question_answer 25)
A particle A of mass m and initial velocity v m collides with a particle B of mass \[\frac{m}{2}\] which is at rest. The collision is head on, and elastic. The ratio of the de-Broglie wavelengths \[{{\lambda }_{A}}\] to \[{{\lambda }_{B}}\] after the collision is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 26)
A mono chromatic source of light operating at 400 w emits \[8\times {{10}^{20}}\] photons per second, the wavelength of light is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 27)
A point source of light is placed at the centre of curvature of a hemispherical surface. The radius of curvature is R and the inner surface is completely reflecting The force on the hemisphere due to the light falling on it if the source emits a power P [c is the speed of light ]
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 28)
An \[\alpha \]-particle having a de-Broglie wavelength \[{{\lambda }_{i}}\] collides with a stationary carbon nucleus. The \[\alpha \]-particle moves off in a different direction as shown below.
After the collision, the de Broglie wavelengths of the \[\alpha \]-particle and the carbon nucleus are \[{{\lambda }_{f}}\] and \[{{\lambda }_{e}}\] respectively. Which of the following relations about de Broglie wavelengths is correct
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 29)
A photon of frequency/causes the emission of a photoelectron of maximum kinetic energy \[{{E}_{k}}\] from a metal. If a photon of frequency 3f is incident on the same metal, the maximum kinetic energy of the emitted photoelectron
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 30)
A 5 watt source emits monochromatic light of wavelength\[\text{5000 }\overset{\text{o}}{\mathop{\text{A}}}\,\]. When placed 0.5 m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of 1.0 m, the number of photoelectrons liberated will be reduced by a factor of
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 31)
The work functions of metals A and B are in the ratio 1 : 2. If light of frequencies f and 2f are incident on the surfaces of A and B respectively, the ratio of the maximum kinetic energies of photoelectrons emitted is (f is greater than threshold frequency of A, 2f is greater than threshold frequency of B)
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 32)
The fastest photoelectrons emitted from a metallic surface during the photoelectric effect have an energy of 8eV. The same photons when incident on atomic hydrogen, are strongly absorbed, exciting the atoms from the ground state to the first excited state. The work function of the metal is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 33)
An ultraviolet light bulb, emitting 400 nm and an infrared light bulb, emitting at 700nm, each are rated at 130 W. Then the ratio of the number of photons emitted per second by the UV and IR sources is -
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 34)
A source of light is placed at a distance of 50 cm from a photocell and the stopping potential is found to be \[{{V}_{0}}\]. If the distance between the light source and photocell is made 25 cm, the new stopping potential will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 35)
A sensor is exposed for time t to a lamp of power P placed at a distance l. The sensor has an opening that is 4d in diameter. Assuming all energy of the lamp is given off as light, the number of photons entering the sensor if the wavelength of light is X is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 36)
The cathode of a photoelectric cell is changed such that the work function changes from \[{{W}_{1}}\] to \[{{W}_{2}}({{W}_{2}}>{{W}_{1}}).\] If the current before and after changes are \[{{I}_{1}}\] and \[{{I}_{2}}\]. all other conditions remaining unchanged, then (assuming \[hv>{{W}_{2}}\])
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 37)
In a photo-emissive cell, with exciting wavelength\[\lambda \], the maximum kinetic energy of electron is K. If the exciting wavelength is changed to \[3\lambda /4\] the kinetic energy of the fastest emitted electron will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 38)
A photoelectric cell is illuminated by a point source of light 1m away. When the source is shifted to 2m then
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 39)
The maximum kinetic energy of the electrons hitting a target so as to produce X-ray of wavelength 1 A is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 40)
When the X-ray tube is operated at 1kV, then X- rays of minimum wavelength \[\text{6}\text{.22 }\overset{\text{o}}{\mathop{\text{A}}}\,\] are produced. If the tube is operated at 10 kV, then the minimum wavelength of x-rays will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 41)
Which one of the following statements is WRONG in the context of X-rays generated from an X-ray tube?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 42)
X-rays are produced in an X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays has values from
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 43)
The ratio of energies of X-rays of the wavelength \[\text{0}\text{.01}\overset{\text{o}}{\mathop{\text{A}}}\,\]and \[\text{0}\text{.5}\overset{\text{o}}{\mathop{\text{A}}}\,\] will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 44)
An x-ray tube is operating at 30 KV then the minimum wavelength of the x-rays coming out of the tube is -
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 45)
A parallel beam of electrons travelling in x-direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum p in the y-direction then for a majority of electrons passing through the slit (h is Planck's constant):
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 46)
The potential difference applied to an X-ray tube is 5kV and the current through it is 3.2mA. Then the number of electrons striking the target per second is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 47)
When the minimum wavelength of X-rays is 2A then the applied potential difference between cathode and anticathode will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 48)
A horizontal cesium plate (work function = 1.9 eV) is moved vertically downward at a constant speed V in a room full of radiation of wavelength 250 nm and above. The minimum value of v so that the vertically upward component of velocity is no positive for each photoelectron.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 49)
The energy in monochromatic X-rays of wavelength 1 A is roughly equal to
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 50)
The short wavelength limit of continuous X-radiation emitted by an X-ray tube operating at 30 kV is 0.414 A. Calculate Planck's constant.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 51)
A particle having mass \[1.67\times {{10}^{-27}}\] kg moving at a speed v absorbs a photon of wavelength 122 nm and stops. The value of v is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 52)
Electrons with energy 80 keV are incident on the tungsten target of an X-ray tube. K-shell electrons of tungsten have 72.5 keV energy. X- rays emitted by the tube contain only
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 53)
An X-ray tube is operated at 15 kV. Calculate the upper limit of the speed of the electrons striking the target.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 54)
Thickness of the medium \[(\mu )\] at which intensity of emergent x-rays becomes half is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 55)
When X-rays of wavelength 0.5 A would be transmitted by an aluminum tube of thickness 7 mm, its intensity remains one-fourth. The absorption coefficient of aluminum for these X-rays is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 56)
An X-ray tube with Cu target is operated at 25 kV. The glancing angle for a \[NaCl.\] Crystal for the \[Cu\]\[{{K}_{\alpha }}\] line is \[15.8{}^\circ \]. Find the wavelength of this line. (\[NaCl=2.82\overset{\text{o}}{\mathop{\text{A}}}\,\] for, \[\text{h=6}\text{.62 }\!\!\times\!\!\text{ 1}{{\text{0}}^{-\,27}}\text{erg-sec}\])
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 57)
The threshold wavelength of the tungsten is 2300 If ultraviolet light of wavelength \[1800\text{ }\overset{\text{o}}{\mathop{\text{A}}}\,\] is incident on it, then the maximum kinetic energy of photoelectrons would be about
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 58)
Two identical photocathodes receive light of frequencies \[{{f}_{1}}\] and\[{{f}_{2}}\]. If the velocities of the photo electrons (of mass m) coming out are respectively
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 59)
When photons of wavelength \[{{\lambda }_{1}}\] are incident on an isolated sphere, the corresponding stopping potential is found to be V. When photons of wavelength \[{{\lambda }_{2}}\] are used, the corresponding stopping potential was thrice that of the above value. If light of wavelength \[{{\lambda }_{3}}\] is used then find the stopping potential for this case:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 60)
Photons with energy 5 eV are incident on a cathode C, on a photoelectric cell. The maximum energy of the emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A if the stopping potential of A relative to C is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 61)
According to Einstein?s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Versus the frequency, of the incident radiation gives a straight line whose slope
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 62)
1.5 mW of 400 nm light is directed at a photoelectric cell. If 0.10 per cent of the incident photons produce photoelectrons, then find the current in the cell.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 63)
Photoelectrons are ejected from a metal when light of frequency \[\nu \] falls on it. Pick out the wrong statement from the following.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 64)
If an electron is accelerated through a potential difference 150 volt, its de-Broglie wavelength is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 65)
The photoelectric threshold wavelength of silver is \[3250\times {{10}^{-10}}m.\]The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength \[2536\times {{10}^{-10\,}}\]m is (Given\[h=4.14\times {{10}^{-15}}eV\text{ and }c=3\times {{10}^{8}}m{{s}^{-1}}\])
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 66)
An atom emits a photon of wavelength X = 600 m by transition from an excited state of life time\[8\times {{10}^{-9}}s\]. If \[\Delta \,v\] represents the minimum uncertainty in the frequency of the photon, the fractional width \[\frac{\Delta v}{v}\] of the spectral line is of the order of
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 67)
Find the number of photon emitted per second by a 25 watt source of monochromatic light of wavelength \[\text{6600 }\overset{\text{o}}{\mathop{\text{A}}}\,\text{.}\] What is the photoelectric current assuming 3% efficiency for photoelectric effect?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 68)
Radiation of two photon energies twice and five times the work function of metal are incident successively on the metal surface. The ratio of the maximum velocity of photoelectrons emitted is the two cases will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 69)
In the photoelectric experiment, if we use a monochromatic light, the I-V curve is as shown. If work function of the metal is 2eV, estimate the power of light used. (Assume efficiency of photo emission \[{{10}^{-3}}%\], i.e., number of photoelectrons emitted are \[{{10}^{-3}}%\]of number of photons incident on metal)
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 70)
Light of wavelength \[\text{200 }\overset{\text{o}}{\mathop{\text{A}}}\,\] fall on aluminum surface. Work function of aluminum is 4.2 eV. What is the kinetic energy of the fastest emitted photoelectrons?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 71)
When a metallic surface is illuminated with radiation of wavelength \[\lambda \], the stopping potential is V. If the same surface is illuminated with radiation of wavelength \[2\lambda \] the stopping potential is \[\frac{V}{4}.\]The threshold wavelength for the metallic surface is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 72)
A beam of light has two wavelengths of \[\text{4972}\overset{\text{o}}{\mathop{\text{A}}}\,\] and \[6216\overset{\text{o}}{\mathop{\text{A}}}\,\] with a total intensity of \[3.6\times {{10}^{-3}}W{{m}^{-2}}\] equally distributed among the two wavelengths. The beam falls normally on an area of \[1c{{m}^{2}}\] of a clean metallic surface of work function 2.3eV. Assume that there is no loss of light by reflection and that each capable photon ejects one electron. The number of photoelectrons liberated in 2s is approximately.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 73)
At t=0, light of intensity \[{{10}^{12}}\]\[{{10}^{12}}photons/s-{{m}^{2}}\]of energy 6eV per photon start falling on a plate with work function 2.5eV. If area of the plate is \[2\times {{10}^{-4}}{{m}^{2}}\]and for every \[{{10}^{5}}\]photos one photoelectron is emitted, charge on the plate at \[t=25s\] is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 74)
The work function for sodium surface is 2.0 eV and that for aluminum surface is 4.2 eV. The two metal are Illuminated with appropriate radiation so as to cause photoemission. Then
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 75)
Light coming from a discharge tube filled with hydrogen falls on the cathode of the photoelectric cell. The work function of the surface of cathode is 4eV. Which of the following values of the anode voltage (in volts) with respect to the cathode will likely to make the photo current zero?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 76)
In an experiment on photoelectric effect, a student plots stopping potential \[{{V}_{0}}\] against reciprocal of the wavelength \[\lambda \] of the incident light for two different metal A and B. These are shown in the figure.
Looking at the graphs, you can most appropriately say that:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 77)
A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value, then the maximum KE, of emitted photoelectrons will become
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 78)
The threshold frequency for a metallic surfaces corresponds on an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5V. The incident radiation lies in
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 79)
Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The wavelength of the emitted electron is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 80)
\[{{10}^{-3}}W\] of \[\text{5000}\overset{\text{o}}{\mathop{\text{A}}}\,\]light is directed on a photoelectric cell. If the current in the cell is\[0.16\mu A\]. The percentage of incident photons which produce photoelectrons, is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 81)
The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is: \[\left( hc=1240eV.nm \right)\]
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 82)
For photoelectric emission from certain metal the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 83)
Electromagnetic radiation falls on a metallic body whose work function is 2eV. For a particular radiation of frequency v, the maximum kinetic energy of the photoelectron is found to be 4 eV. What would be the maximum kinetic energy of 5v photoelectron for the radiation of frequency\[\frac{5v}{3}\] ?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 84)
In a photo-emissive cell, with exciting wavelength X, the fastest electron has speed v. If the exciting wavelength is changed to \[\frac{5\lambda }{4}\], the speed of the fastest emitted electron will be
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 85)
In a photoelectric emission, electrons are ejected from metal X and Y by light of frequency f. The potential difference V required to stop the electrons is measured for various frequencies. If Y as a greater work function than X, which graph illustrates the expected results?
A)
B)
C)
D)
View Solution play_arrow
question_answer 86)
The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy 6 eV fall on it is 4 eV. The stopping potential, in volt, is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 87)
A perfectly reflecting solid sphere of radius x is kept in the path of a parallel beam of light of large aperture. If the beam carries an intensity I, find the force exerted by the beam on the sphere.
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 88)
A parallel beam of light of wavelength 600 nm and intensity \[100\text{ }w\text{ }{{m}^{-2}}\]. How many photons cross \[1\text{ }c{{m}^{2}}\] area perpendicular to the beam in 1 sec?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 89)
A point source causes photoelectric effect from a small metal plate. Which of the curves in Fig may represent the saturation photo - current as a function of the distance between the source and the metal?
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 90)
A photoelectric surface is illuminated successively by monochromatic light of wavelengths \[\lambda \] and\[\frac{\lambda }{2}.\] If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 91)
The de Broglie wavelength of an electron is the same as that of a 50 KeV X-ray photon. The ratio of the energy of the photon to the kinetic energy of the electron is: (the energy equivalent of electron mass is 0.5 MeV)
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 92)
A 200 W sodium street lamp emits yellow light of wavelength \[0.6\,\mu m\]. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 93)
Photoelectric emission is observed from a metallic surface for frequencies \[{{v}_{1}}\] and \[{{v}_{2}}\] of the incident light rays\[\left( {{v}_{1}}>{{v}_{2}} \right)\]. If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of 1:k, then the threshold frequency of the metallic surface is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 94)
A material particle with a rest mass \[{{m}_{0}}\]is moving with a velocity of light c. Then the wavelength of the de Broglie wave associated with is is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 95)
To decrease the cut-off wavelength of continuous X-rays by 25%, the potential difference across X-ray tube
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 96)
The shortest wavelength of X-ray emitted from an X-ray tube operated at \[2\times {{10}^{6}}volt\]is of the order of
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 97)
De-Broglie wavelength associated with the hydrogen atom moving with most probable velocity at \[27{}^\circ C\] is \[1.26\overset{\text{o}}{\mathop{\text{A}}}\,\]. De-Broglie wavelength associated with helium atom moving with r.m.s. velocity at \[51{}^\circ C\] is:
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 98)
Two identical non-relative particles A and B move right angles to each other, processing de Broglie wavelength \[{{\lambda }_{1}}\] and \[\,{{\lambda }_{2}}\], respectively. The de Broglie wavelength of each particle in their center of mass frame of reference is
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 99)
The ratio of the \[{{\lambda }_{\min }}\]in a Coolidge tube to \[{{\lambda }_{deBroglie}}\] of the electrons striking the target depends on accelerating potential V as
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
question_answer 100)
In a photoelectric experiment, anode potential is plotted against plate current in figure. Then
A)
done
clear
B)
done
clear
C)
done
clear
D)
done
clear
View Solution play_arrow
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
done
clear
After the collision, the de Broglie wavelengths of the \[\alpha \]-particle and the carbon nucleus are \[{{\lambda }_{f}}\] and \[{{\lambda }_{e}}\] respectively. Which of the following relations about de Broglie wavelengths is correct 
Looking at the graphs, you can most appropriately say that: 
