Class 12 Current Electricity CBSE Questions & Answers

Class 12 · Current Electricity

This is Physics Class 12 Current Electricity CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Two cells of 1.25 V and 0.75 V are connected in parallel with anode of one connected to cathode of the other . The effective voltage will be
  • A
    0.50 V
  • B
    2.0 V
    Correct
  • C
    0.75 V
  • D
    1.25 V
2
Two cells of 1.25 V and 0.75 V are connected in parallel with anode of one connected to anode of the other . The effective voltage will be
  • A
    2.0 V
  • B
    0.50 V
    Correct
  • C
    0.75 V
  • D
    1.25 V
3
A current of 2 A flows in conductors as shown. The potential difference VA- VB will be
Question 3 figure 1
  • A
    \(-{\rm{ 1 V}}\)
  • B
    \( + {\rm{ 4 V}}\)
  • C
    \( + {\rm{ 1 V}}\)
    Correct
  • D
    \( + {\rm{ 2 V}}\)
4
The instrument for the accurate measurement of the e.m.f of a cell is
  • A
    a potentiometer
    Correct
  • B
    an ammeter
  • C
    a slide wire bridge
  • D
    a voltmeter
5
Potentiometer measures the potential difference more accurately than a voltmeter, because
  • A
    It does not draw current from external circuit.
    Correct
  • B
    it has a wire of high resistance
  • C
    it has a wire of low resistance.
  • D
    It draws a heavy current from external circuit.
6
In a potentiometer experiment, for measuring internal resistance of a cell, the balance point has been obtained on the fourth wire. The balance point can be shifted to fifth wire by
  • A
    Putting a shunt resistance in parallel with the cell.
  • B
    putting a suitable resistance in series with the cell.
  • C
    decreasing the current due to auxiliary battery
    Correct
  • D
    increasing the current due to auxiliary battery
7
It is observed in a potentiometer experiment that no current passes through the galvanometer, when the terminals of the cell are connected across a certain length of the potentiometer wire. On shunting the cell by a 2 Ω resistance, the balancing length is reduced to half. The internal resistance of the cell is
  • A
    4 \(_\Omega \)
  • B
    9 \(_\Omega \)
  • C
    2 \(_\Omega \)
    Correct
  • D
    18 \(_\Omega \)
8
The sensitivity of the potentiometer can be increased by:
  • A
    decreasing the length of potentiometer wire.
  • B
    increasing the e.m.f. of primary cell.
  • C
    increasing the potential gradient.
  • D
    increasing the length of potentiometer wire.
    Correct
9
Two resistances are connected in the two gaps of a meter bridge. The balance points is 20 cm from the zero end. When a resistance of 15 ohm is connected in series with the smaller of the two resistances, the null point shifts to 40 cm. The smaller of the two resistances has the value (in ohm)
  • A
    9.0
    Correct
  • B
    12
  • C
    10
  • D
    8
10
Kirchhoff’s second law is a consequence of
  • A
    Law of conservation of angular momentum
  • B
    Law of conservation of energy
    Correct
  • C
    Law of conservation of momentum
  • D
    Law of conservation of charge
11
In a meter bridge, when galvanometer & cell positions are interchanged
  • A
    Inverse relation between four resistance is got
  • B
    Exactly same relation between four resistance is got
    Correct
  • C
    No relation is got between four resistances
  • D
    Can’t predict the relation
12
An ammeter together with an unknown resistance in series is connected across two identical batteries each of emf 1.5 V. When the batteries are connected in series, the galvanometer records a current of 1A and when the batteries are in parallel, the current is 0.6A. Then the internal resistance of the battery is
  • A
    \({1 \over 3}\Omega \)
    Correct
  • B
    \({1 \over 4}\Omega \)
  • C
    . \({1 \over 2}\Omega \)
  • D
    \({1 \over 5}\Omega \)
13
A battery is connected with a potentiometer wire. The internal resistance of the battery is negligible. If the length of the potentiometer wire of the same material and radius is doubled then
  • A
    Potential gradient becomes half
  • B
    Potential gradient becomes two times
  • C
    None of these
  • D
    Potential gradient does not change
    Correct
14
A potential difference of 220 V is maintained across 12000 \(_{\Omega }\) rheostat. Then voltmeter V has a resistance of 6000 \(_{\Omega }\) and point C is at one fourth the distance from a to b. Then the reading of voltmeter is
Question 14 figure 1
  • A
    30 volt
  • B
    45 volt
  • C
    60 volt
  • D
    40 volt
    Correct
15
Figure shows current in a part of an electrical circuit. Then current I is
Question 15 figure 1
  • A
    1.5 A
  • B
    2.5A
    Correct
  • C
    0.5A
  • D
    2.1A