Write the following radiations in ascending order with respect to their frequencies: |
X-rays, Microwaves, UV rays and Radio waves. |
Lakshmi, Seema's domestic helper was complaining for few days about the ill health of his son Lakshman. After conversing with Lakshmi, Seema came to know that Lakshman is a regular worker in a nuclear power plant. Since, Lakshmi was ignorant about the nuclear radiation caused in nuclear power plant which causes occupational hazard and finally convinced her to get Lakshman admitted in hospital and start treatment. |
Read the above passage and answer the following questions |
(i) Which possible reasons were responsible for deterioration of Lakshman's health? Write any one characteristic of such radiation. |
(ii) Write any two values that reflected in Seema's advice. |
A cell of emf 'E' and internal resistance r is connected across a variable resistor R. Plot a graph showing the variation of terminal potential V with resistance R. Predict from the graph, the condition under which V becomes equal to E. |
OR |
Apply Kirchhoff's laws to the loops ACBPA and ACBQA to write the expressions for the currents \[{{I}_{1}},{{I}_{2}}\] and \[{{I}_{3}}\] in the network given below. |
Circuit diagram of loops |
Give reason of the following |
(i) The momentum that is transferred by an electromagnetic wave on a surface is very small. |
(ii) Childrens are always warned to not to look directly from their naked eyes when a welder is welding a part of a machine. |
In Mumbai, a multistoried building, once a fire broke out at 2 : 00 AM due to some electrical problem. Ram alongwith others rushed to the spot, informed the fire department. Ram being secretary of the building decided to fix fire alarms in the building. |
(i) What values were shown by Ram? |
(ii) On which principle fire alarms work? |
Write down the equation of that principle, |
(i) Using the Bohr's model, calculate the speed of the electron in a H-atom in the n = 1, 2 and 3 levels. |
(ii) Calculate the orbital period in each of these levels. |
A seminar was conducted on renewable sources of energy, where Romilla gave an motivating speech on 'solar cell' to create awareness among students guided by her Physics teacher. |
Read the above passage and answer the following questions : |
(i) State the reason, why GaAs is most commonly used in making a solar cell. |
(ii) What values are exhibited by Romilla? |
(iii) How does photocurrent is produced by solar cells? |
Potentiometer wire PQ of 1 m length is connected to a standard cell \[{{E}_{1}}.\] Another cell \[{{E}_{2}},\] of emf 1.02 V is connected as shown in the circuit. Diagram with a resistance, r and a switch, S. With switch S open, null point is obtained at a distance of 51 cm from P. |
Potentiometer Calculate |
(i) potential gradient of the potentiometer wire. |
(ii) emf of the cell \[{{E}_{1}}.\] |
(iii) when switch S is closed, will null point moves towards P or towards Q ? Give reason, |
Shikha went to the market with her brotherly metro. While passing through a gateway for security check she heard a long beep, as it was a metal detector which beeped. She was curious and asked about understood the reason of beeping from her class teacher. Read the above passage and answer the following questions : |
(i) On which principle does a metal detector work? What causes production of a beep in this case? |
(ii) Can the voltage drop across the inductor or the capacitor in a series L-C-R circuit be greater than the applied voltage of the AC source? Justify your answer. |
(iii) Write one value displayed by Shikha. |
Using the data given below, state which two of the given lenses will you prefer to construct a best possible |
(i) telescope |
(ii) compound microscope. |
Also, indicate which of the selected lenses is to be used as an objective and as an eye lens in each case. |
Lens | Power (P) | Aperture (A) |
\[{{L}_{1}}\] | 6 D | 1 cm |
\[{{L}_{2}}\] | 3 D | 8 cm |
\[{{L}_{3}}\] | 10 D | 1 cm |
A beam of light consisting of two wavelengths 650 nm and 520 nm, is used to obtain interference fringes in Young's double slit experiment. |
(i) Find the distance of the third bright fringe on the screen from the central maximum for the wavelength 650 nm. |
(ii) What is the least distance from the central maximum where the bright fringes due to both wavelengths coincide? |
The distance between the two slits is 2 mm and the distance between the plane of the slits and the screen is 120 cm. |
(i) The number of nuclei of a given radioactive sample at time t = 0 and t =T are \[{{N}_{0}}\] and \[{{N}_{0}}/n,\] respectively. Obtain an expression for the half-life \[({{T}_{1/2}})\] of the nucleus in terms of n and T. |
(ii) Write the basic nuclear process underlying \[{{\beta }^{-}}\text{-}decay\]of a given radioactive nucleus. |
(iii) Differentiate between \[{{\beta }^{+}}\] and \[{{\beta }^{-}}\]-decay. |
OR |
Define the terms: |
(i) Mass defect. |
(ii) Binding energy for a nucleus and state the relation between the two, for a given nuclear reaction the binding energy per nucleon of the product nucleus is more than that for the original nucleus, is this nuclear reaction exothermic or endothermic in nature? |
(iii) What is the role of control rods in a nuclear reactor? Why are they made of cadmium? |
(i) Write the function of |
(a) Transducer and |
(b) Repeater in the context of communication system. |
(ii) Write two factors justifying the need of modulation for transmission of a signal. |
Output characteristics of an n-p-n transistor in CE configuration is shown in the below figure. Determine : |
(i) DC current gain. |
(ii) Dynamic output resistance. |
(iii) AC current gain at an operating point, |
\[{{V}_{CE}}=10V,\,\,when\,\,{{I}_{B}}=30\mu A.\] |
A parallel plate capacitor is charged to a potential difference V by a DC source, The capacitor is then disconnected from the source. If the distance between the plates is tripled, state with reason, how the following will change? |
(i) Charge on capacitor |
(ii) Electric potential and field between the plates. |
(iii) Energy stored in the capacitor |
An electron emitted by a heated cathode and accelerated through a potential difference of 2 kV, enters a region with a uniform magnetic field of 0.15 T. Determine the trajectory of the electrons if the magnetic field |
(i) is transverse to its initial velocity. |
(ii) makes an angle \[30{}^\circ \] with the initial velocity. |
Derive an expression for the potential energy of an electric dipole placed in a uniform electric field. Hence, discuss the conditions of stable and unstable equilibrium. |
Or |
Four charges are arranged at the corners of a square ABCD of side d as shown in the figure. |
(i) Find the work required to put together this arrangement. |
(ii) A charge \[{{q}_{0}}\] is brought to the centre E of the square, the four charges being held fixed at its corners. How much extra work is needed to do this? |
(iii) Compute the work done by the charges in rearranging this arrangement of to another similar square arrangement of the charges such that the side of the square now becomes 2d. |
(i) State the condition for resonance to occur in a series L-C-R AC circuit and derive an expression for the resonant frequency. Draw the plot showing the variation of the peak current \[({{I}_{m}})\] with frequency of the AC source used. Also define the quality factor Q of the circuit. |
(ii) Calculate the (a) impedance (b) wattles current of the given AC circuit. |
Or |
(i) Mention the reasons for energy losses in an actual transformer. |
(ii) The power transmission lines needs input power at 2300 V to a step down transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary windings in order to get output power at 230 V. |
(i) What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses. |
(ii) At what angle should a ray of light be incident on the face of a prism of refracting angle \[60{}^\circ ,\] so that it just suffers total internal reflection at the other face? |
The refractive index of the material of the prism is 1.524. |
Or |
(i) Define the power of lens. |
(ii) An angular magnification (magnifying power) of 24 X is desired using an objective of focal length 1.25 cm and an eyepiece of focal length 5 cm. How will you set up the compound microscope? |
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