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
In the measurement of resistance by a metre bridge, the current is necessarily reversed through the bridge wire to eliminate
  • A
    Index errors
  • B
    Error due to thermoelectric effects
  • C
    Random errors
  • D
    End errors
    Correct
2
If 2% of the main current is to be passed through the galvanometer of resistance G, the resistance of shunt required is
  • A
    G/50
  • B
    50G
  • C
    G/49
    Correct
  • D
    49G
3
In the figure, when an ideal voltmeter is connected across 4000 ohm resistance, it reads 30 volts. If the voltmeter is connected across 3000 ohms resistance. It will read
Question 3 figure 1
  • A
    40 volt
  • B
    20 volt
  • C
    22.5 volt
    Correct
  • D
    35 volt
4
According to Ohm's law
  • A
    The electric current I flowing through a substance is inversely proportional to the voltage V across its ends
  • B
    The electric current I flowing through a substance is proportional to the square of voltage V across its ends
  • C
    The electric current I flowing through a substance is independent of the voltage V across its ends
  • D
    The electric current I flowing through a substance is proportional to the voltage V across its ends
    Correct
5
Drift is the random motion of the charged particles within a conductor,
  • A
    along with accelerated motion in the direction of the field
  • B
    along with a decelerated motion in the direction of the field
  • C
    along with a very slow net motion in the direction of the field
    Correct
  • D
    along with zero motion in the direction of the field
6
orders of magnitude of random electron motion speed to drift speed are like
  • A
    ${\text{1}}{0^{\text{3}}}{\text{m}}/{\text{s}},{\text{1}}{0^{ - {\text{1m}}/{\text{s}}}}$
  • B
    ${\text{1}}{0^{\text{4}}}{\text{m}}/{\text{s}},{\text{1}}{0^{ - {\text{2}}}}{\text{m}}/{\text{s}}$
  • C
    ${\text{1}}{0^{\text{2}}}{\text{m}}/{\text{s}},{\text{1}}{0^{\text{2}}}{\text{m}}/{\text{s}}$
  • D
    ${\text{1}}{0^{\text{6}}}{\text{m}}/{\text{s}},{\text{1}}{0^{ - {\text{4}}}}{\text{m}}/{\text{s}}$
    Correct
7
The resistance of a metallic conductor increases due to
  • A
    increase in the rate of collisions between the carriers and vibrating atoms of the conductor
  • B
    Change in carrier density
  • C
    Change in dimensions of the conductor
    Correct
  • D
    increase in the number of collisions between the carriers
8
A piece of copper and another of germanium are cooled from room temperature to 80K. The resistance
  • A
    copper decreases and that of germanium increases
    Correct
  • B
    of each of them increases
  • C
    of each of them decreases
  • D
    copper increases and that of germanium decreases
9
Power dissipated in a resistance R through which current I is flowing is
  • A
    IR
  • B
    ${{\text{I}}^{\text{2}}}{\text{R}}$
    Correct
  • C
    ${\text{I}}{{\text{R}}^{\text{2}}}$
  • D
    ${{\text{I}}^{\text{2}}}{{\text{R}}^{\text{2}}}$
10
The equivalent resistance of two resistances P and Q which are in series is
  • A
    P + Q
    Correct
  • B
    PQ/(P + Q)
  • C
    ${\text{P}} \times {\text{P}}/\left( {{\text{P}} + {\text{Q}}} \right)$
  • D
    Q×Q/(P + Q)
11
The equivalent resistance of two resistances P and Q which are in parallel is
  • A
    PQ/(P+Q)
    Correct
  • B
    Q×Q/(P + Q)
  • C
    P×P/(P + Q)
  • D
    P + Q
12
According to Kirchhoff’s Junction Rule
  • A
    At any junction of circuit elements, the sum of currents entering and leaving the junction must be negative.
  • B
    At any junction of circuit elements, the sum of currents entering and leaving the junction must be positive.
  • C
    At any junction of circuit elements, sum of some of the currents entering the junction may be positive or negative.
  • D
    At any junction of circuit elements, the sum of currents entering the junction must equal the sum of currents leaving it.
    Correct
13
Direction of the conventional current
  • A
    is the direction in which positive charges move
    Correct
  • B
    is the direction in which no charges move
  • C
    to the direction in which positive charges move
  • D
    is the direction in which negative charges move
14
The equivalent emf of two sources of voltages E1 and E2 which are in series with cathode of one connected to anode of the other is
  • A
    ${{\text{E}}_{\text{2}}} \times {{\text{E}}_{\text{2}}}/\left( {{{\text{E}}_{\text{1}}} + {{\text{E}}_{\text{2}}}} \right)$
  • B
    ${{\text{E}}_{\text{1}}} + {{\text{E}}_{\text{2}}}$
    Correct
  • C
    ${{\text{E}}_{\text{1}}}{{\text{E}}_{\text{2}}}/\left( {{{\text{E}}_{\text{1}}} + {{\text{E}}_{\text{2}}}} \right)$
  • D
    ${{\text{E}}_{\text{1}}} \times {{\text{E}}_{\text{1}}}/\left( {{{\text{E}}_{\text{1}}} + {{\text{E}}_{\text{2}}}} \right)$
15
If P and Q are two batteries connected in series with anode of one connected to anode of the other, producing voltages E1 and ${{\text{E}}_{\text{1}}} > {{\text{E}}_{\text{2}}}$ respectively and the e m f of the pair is
  • A
    ${{\text{E}}_{\text{2}}}$
  • B
    ${{\text{E}}_{\text{1}}}$
  • C
    ${{\text{E}}_{\text{2}}} - {{\text{E}}_{\text{1}}}$
    Correct
  • D
    ${{\text{E}}_{\text{2}}} + {{\text{E}}_{\text{1}}}$