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
Resistance of a conductor is
  • A
    product of voltage and current
  • B
    ratio of voltage to current
    Correct
  • C
    ratio of current to voltage
  • D
    product of voltage and conductivity
2
In the circuit shown, the cell has e m f = 10 V and internal resistance = ${\text{1}}\Omega $
Question 2 figure 1
  • A
    The current through the $4 - \Omega $resistor is 0.5 A.
  • B
    The current through the $3 - \Omega $resistor is 1 A.
    Correct
  • C
    The current through the $4 - \Omega $resistor is 0.25 A.
  • D
    The current through the $3 - \Omega $resistor is 0.5 A.
3
In the circuit shown below, the cell is ideal, with emf = 2 V. The resistance of the coil of the galvanometer G is $1\Omega $
Question 3 figure 1
  • A
    No current flows in G.
    Correct
  • B
    Potential difference across C1 is 1 V.
  • C
    0.2 A current flows in G.
  • D
    Potential difference cross C2 is 1.2 V.
4
Three voltmeters, all having different resistances, are joined as shown. When some potential difference is applied across A and B, their readings are V1, V2 , V3 .
Question 4 figure 1
  • A
    V1+V2=V3
    Correct
  • B
    V1=V2
  • C
    ${\text{V1}} \ne {\text{V2}}$
  • D
    V1+V2>V3
5
electromotive force is
  • A
    The work done per unit charge by the source in taking the charge from lower to higher potential energy
    Correct
  • B
    The work done per unit charge by the source in taking the charge from higher to lower potential energy
  • C
    The work done by the source in taking the charge from lower to higher potential energy
  • D
    The number of charges pumped by the source from lower to higher potential energy
6
A milliammeter of range 10 mA and resistance is joined in a circuit as shown. The device gives full-scale deflection for current I when A and B are used as its terminals, i.e., current enters at A and leaves at B (C is left isolated). The value of I is
Question 6 figure 1
  • A
    900 mA
  • B
    1.1 A
  • C
    1 A
    Correct
  • D
    100 mA
7
Current density of a conductor is
  • A
    Is always zero
  • B
    the net charge flowing through the area normally per unit time
    Correct
  • C
    the net charge flowing through the area per unit time
  • D
    the net charge flowing through the area
8
mobility is defined as
  • A
    the magnitude of the drift velocity per unit electric field
    Correct
  • B
    the magnitude of the drift velocity per unit charge
  • C
    the magnitude of the drift velocity per unit voltage
  • D
    the number of charges in motion per unit electric field
9
The wire of the potentiometer has resistance 4 ohms and length 1 m. It is connected to a cell of e.m.f. 2 volts and internal resistance 1 ohm. The current flowing in the potentiometer is:
  • A
    0.4 A
    Correct
  • B
    0.2 A
  • C
    0.1 A
  • D
    0.8 A
10
The wire of the potentiometer has resistance 4 ohms and length 1 m. It is connected to a cell of e.m.f. 2 volts and internal resistance 1 ohm. The p.d. across the potentiometer wire is:
  • A
    1.2 V
  • B
    0.8 V
  • C
    2.0 V
  • D
    1.6 V
    Correct
11
The wire of the potentiometer has resistance 4 ohms and length 1 m. It is connected to a cell of e.m.f. 2 volts and internal resistance 1 ohm, the potential gradient in the potentiometer wire is:
  • A
    2.0 volt/m
  • B
    0.8 volt/m
  • C
    1.2 volt/m
  • D
    1.6 volt/m
    Correct
12
The wire of the potentiometer has resistance 4 ohms and length 1 m. It is connected to a cell of e.m.f. 2 volts and internal resistance 1 ohm, if a cell of e.m.f. 1.2 volt is balanced by it, the balancing length will be
  • A
    90 cm
  • B
    50 cm
  • C
    75 cm
    Correct
  • D
    60 cm
13
A potentiometer has a uniform wire of length 10m and resistance . The potentiometer is connected to an external battery of emf of 10V and negligible internal resistance and a resistance of in series. The potential gradient along the were is:
  • A
    1 mV/m
  • B
    5 mV/cm
  • C
    1 mV/cm
  • D
    5 mV/m
    Correct
14
A potentiometer wire, 10 m long, has resistance 40 ohms. It is put in series with a resistance 760 ohms and connected to a 2 volt battery. The potential gradient in the wire is :
  • A
    $1 \times {10^{ - {\text{3}}}}volt/m$
  • B
    $1 \times {10^{ - {\text{2}}}}volt/m$
    Correct
  • C
    $1 \times {10^{ - {\text{4}}}}volt/m$
  • D
    $1 \times {10^{ - {\text{6}}}}volt/m$
15
In a Wheatstone’s bridge, P = 9 ohms, Q = 11 ohms, R = 4 ohms and S = 6 ohms. How much resistance must be put in parallel to the resistance S to balance the bridge?
  • A
    24 ohms
  • B
    18.7 ohms
  • C
    26.4 ohms
    Correct
  • D
    (44/9) ohms