12th Class Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank

done MCQs - Current Electricity Total Questions - 21

• question_answer1)
  Consider a current carrying wire (current I) in the ape of a circle. Note that as the current progresses along the wire, the direction of j (current density) change' in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is
  A)
  source of emf. done clear
  B)
  electric field produced by charges accumulated on the surface of wire. done clear
  C)
  the charges just behind a given segment of Wire which push them just the right way by repulsion. done clear
  D)
  the charges ahead. done clear
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• question_answer2)
  Which of the following characteristics of electrons determines the current in a conductor?
  A)
  Drift velocity alone done clear
  B)
  Thermal velocity alone done clear
  C)
  Both drift velocity and thermal velocity done clear
  D)
  Neither drift nor thermal velocity. done clear
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• question_answer3)
  A metal rod of length 10 cm and a rectangular cross - section of 1 cm \[\times \frac{1}{2}\] cm is connected to a battery across opposite faces. The resistance will be
  A)
  maximum when the battery is connected across 1 cm \[\times \frac{1}{2}\] cm faces. done clear
  B)
  maximum when the battery is connected across 10 cm \[\times \]1 cm faces. done clear
  C)
  maximum when the battery is connected across 10 cm \[\times \frac{1}{2}\] cm faces. done clear
  D)
  same irrespective of the three faces. done clear
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• question_answer4)
  When cell of e.m.f. E is connected with an external resistance R, the p.d. across the cell becomes V. The expression for the internal resistance of the cell is
  A)
  \[\frac{E\ -V}{V}R\] done clear
  B)
  \[{{10}^{23}}\] done clear
  C)
  \[\frac{V-E}{V}R\] done clear
  D)
  \[\frac{V-E}{\operatorname{E}}R\] done clear
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• question_answer5)
  The current density (number of free electrons per \[{{\operatorname{m}}^{3}}\]) in metallic conductor is of the order of
  A)
  \[{{10}^{28}}\] done clear
  B)
  \[{{10}^{23}}\] done clear
  C)
  \[{{10}^{20}}\] done clear
  D)
  \[{{10}^{15}}\] done clear
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• question_answer6)
  Which of the following I-V characteristic represent the characteristic of a Ohmic conductor?
  A)
  done clear
  B)
  done clear
  C)
  done clear
  D)
  done clear
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• question_answer7)

  What is the potential difference between points A and B in the following circuit?

  A)
  10 V done clear
  B)
  5 V done clear
  C)
  2.5 V done clear
  D)
  20 V done clear
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• question_answer8)

  Two batteries of emf \[{{\varepsilon }_{1}}\] and \[{{\varepsilon }_{2}}\] \[({{\varepsilon }_{2}}>{{\varepsilon }_{1}})\] and internal resistances \[{{r}_{1}}\] and \[{{r}_{2}}\] respectively are connected in parallel as shown in figure :

   
  A)
  The equivalent emf \[{{\varepsilon }_{\operatorname{eq}}}\] of the two cells is between \[{{\varepsilon }_{1}}\] and \[{{\varepsilon }_{2}},\ i.e.{{\varepsilon }_{1}}<{{\varepsilon }_{\operatorname{eq}}}<{{\varepsilon }_{2}}\] done clear
  B)
  The equivalent emf \[{{\varepsilon }_{\operatorname{eq}}}\] is smaller than \[{{\varepsilon }_{1}}\]. done clear
  C)
  The \[{{\varepsilon }_{\operatorname{eq}}}\] is given by \[{{\varepsilon }_{\operatorname{eq}}}\]=\[{{\varepsilon }_{1}}\]+ \[{{\varepsilon }_{2}}\] always. done clear
  D)
  \[{{\varepsilon }_{\operatorname{eq}}}\] is independent of internal resistances \[{{r}_{1}}\] and \[{{r}_{2}}\] done clear
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• question_answer9)
  A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100\[\Omega \]. He finds the null point at \[{{l}_{1}}\] = 2.9 cm. He is told to attempt to improve the accuracy. Which or the following is a useful way?
  A)
  He should measure \[{{l}_{1}}\] more accurately. done clear
  B)
  He should change S to 1000\[\Omega \]  and repeat the experiment. done clear
  C)
  He should change S to 3 \[\Omega \] and repeat the experiment. done clear
  D)
  He should give up hope of a more accurate measurement with a meter bridge. done clear
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• question_answer10)
  Two cells of emf's approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm:
  A)
  The battery that runs the potentiometer should have voltage of 8 V. done clear
  B)
  The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V done clear
  C)
  The first portion of 50 cm of wire itself should have a potential drop of 10 V. done clear
  D)
  Potentiometer is usually used for comparing resistances and not voltages. done clear
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• question_answer11)
  Kirchhoff's current law is based on the law of conservation of
  A)
  charge. done clear
  B)
  energy. done clear
  C)
  mass. done clear
  D)
  [b] and [c]       done clear
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• question_answer12)
  Kirchhoff's voltage law is based on the law of conservation of
  A)
  charge done clear
  B)
  energy done clear
  C)
  mass done clear
  D)
  [b] and [c] done clear
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• question_answer13)
  Apply Kirchhoff's law to find the current I in the part of the following circuit.
  A)
  5 A done clear
  B)
  3 A done clear
  C)
  7 A done clear
  D)
  1 A done clear
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• question_answer14)
  Wheatstone Bridge is not suitable for measurement of
  A)
  very high value resistances. done clear
  B)
  very low value resistances. done clear
  C)
  both [a] and [b]. done clear
  D)
  medium value resistances. done clear
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• question_answer15)
  Kirchhoff's laws are valid for ____.
  A)
  only passive circuits done clear
  B)
  only linear circuits done clear
  C)
  only non-linear circuits done clear
  D)
  both [b] and [c]. done clear
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• question_answer16)
  Two resistances are connected in two gaps of Meter Bridge. The balance is 10 cm from the zero end. A resistance of 20 \[\Omega \] is connected in series with the smaller of the two. The null point shifts to 20 cm. What is the value of the bigger resistance?
  A)
  89 \[\Omega \] done clear
  B)
  144\[\Omega \] done clear
  C)
  100\[\Omega \] done clear
  D)
  None of the above done clear
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• question_answer17)
  In a metre bridge, what is the effect on null deflection of galvanometer, when the radius of the meter bridge wire is doubled?
  A)
  There will be no change done clear
  B)
  Null point will shift to \[{{\operatorname{L}}_{1}}\] / 2 point done clear
  C)
  Null point will shift to 2\[{{\operatorname{L}}_{1}}\] point done clear
  D)
  Null point will not be available done clear
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• question_answer18)
  Consider a metre bridge whose length of wire is 2m. A resistance of 10 \[\Omega \] is connected across one gap of the meter bridge and an unknown resistance is connected across the other gap. When these resistances are interchanged, the balance point shifts by 50 cm. What is the value of the unknown resistance?
  A)
  250\[\Omega \] done clear
  B)
  10\[\Omega \] done clear
  C)
  16.7\[\Omega \] done clear
  D)
  None of the above done clear
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• question_answer19)
  Which error of Meter Bridge is removed when the known and unknown resistances are interchanged?
  A)
  End error done clear
  B)
  Measurement error done clear
  C)
  Percentage error done clear
  D)
  Parallax error done clear
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• question_answer20)
  In a potentiometer of 5 wires, the balance point is obtained on the 3rd wire. To shift the balance point to the 4th wire,
  A)
  current of the main circuit is to be decreased. done clear
  B)
  current of the main circuit is to be increased. done clear
  C)
  the shifting is not possible done clear
  D)
  None of the above done clear
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• question_answer21)
  Which one of the following statements is correct?
  A)
  Potentiometer is used to measure the current in a circuit. done clear
  B)
  Potentiometer is used to measure the internal resistance of a cell. done clear
  C)
  Potentiometer is used to measure the resistance of a circuit. done clear
  D)
  Potentiometer is used to measure the potential difference across a resistor. done clear
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