Current Electricity

Current Electricity

Easy Questions

Electricity and Magnetism

Current Electricity
Moving Charges and Magnetism
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  1. In the circuit shown in Fig, the current in 4 Ω resistance is 1.2 A. What is the potential difference between B and C.​​








  1. View Hint View Answer Discuss in Forum

    The potential difference across 4Ω resistance is given by ​V = 4 × i1 = 4 × 1.2 = 4.8 volt ​
    So, the potential across 8Ω resistance is also 4.8 volt.

    Current i2 =
    V
    		=
    4.8
    		=0.6 amp
    88

    Current in 2Ω resistance i = i1 + i2 ​
    ∴ i = 1.2 + 0.6 = 1.8 amp ​
    Potential difference across 2Ω resistance ​
    VBC = 1.8 × 2 = 3.6volts

    Correct Option: A

    The potential difference across 4Ω resistance is given by ​V = 4 × i1 = 4 × 1.2 = 4.8 volt ​
    So, the potential across 8Ω resistance is also 4.8 volt.

    Current i2 =
    V
    		=
    4.8
    		=0.6 amp
    88

    Current in 2Ω resistance i = i1 + i2 ​
    ∴ i = 1.2 + 0.6 = 1.8 amp ​
    Potential difference across 2Ω resistance ​
    VBC = 1.8 × 2 = 3.6volts

  1. Two wires of the same metal have same length, but their cross-sections are in the ratio 3:1. They are joined in series. The resistance of thicker wire is 10Ω. The total resistance of the combination will be​​








  1. View Hint View Answer Discuss in Forum

    Length of each wire = l; Area of thick wire (A1) = 3A; Area of thin wire (A2) = A and resistance of thick wire (R1) = 10 Ω.

    Resistance (R) = ρ
    l
    		∝
    1
    		(if l is constant)
    AA

    ∴R1=A2= A=1
    R2A13A3

    or, R2 = 3R1 = 3 × 10 = 30 Ω ​
    The equivalent resistance of these two resistors in series ​
    = R1 + R2 = 30 + 10 = 40Ω.

    Correct Option: C

    Length of each wire = l; Area of thick wire (A1) = 3A; Area of thin wire (A2) = A and resistance of thick wire (R1) = 10 Ω.

    Resistance (R) = ρ
    l
    		∝
    1
    		(if l is constant)
    AA

    ∴R1=A2= A=1
    R2A13A3

    or, R2 = 3R1 = 3 × 10 = 30 Ω ​
    The equivalent resistance of these two resistors in series ​
    = R1 + R2 = 30 + 10 = 40Ω.

  1. ​What will be the equivalent resistance of circuit shown in figure between two points A and D









  1. View Hint View Answer Discuss in Forum


    = 10 Ω +20 × 20+ 10 = 10 + 10 + 10 = 30 Ω
    20 + 20

    Correct Option: C


    = 10 Ω +20 × 20+ 10 = 10 + 10 + 10 = 30 Ω
    20 + 20

  1. The current in the following circuit is​








  1. View Hint View Answer Discuss in Forum

    Resistance of ACB, R' = 3Ω + 3Ω = 6Ω. ​
    For net resistance between A and B; R' = 6Ω and 3Ω are in parallel.

    RAB =
    3 ×6
    		=
    18
    		= 2 Ω
    3 + 69

    Current in circuit (I) =
    E
    		=
    2
    		= 1 A
    RAB2

    Correct Option: A

    Resistance of ACB, R' = 3Ω + 3Ω = 6Ω. ​
    For net resistance between A and B; R' = 6Ω and 3Ω are in parallel.

    RAB =
    3 ×6
    		=
    18
    		= 2 Ω
    3 + 69

    Current in circuit (I) =
    E
    		=
    2
    		= 1 A
    RAB2

  1. The current (I) in the given circuit is​​








  1. View Hint View Answer Discuss in Forum

    In circuit, RB and RC are in series, so, Rs = 6 + 6 = 12 Ω.
    This 12 Ω resistance is in parallel with RA = 3 Ω, ​
    So, equivalent resistance of circuit

    R =3 × 12 = 36 = 12 Ω
    3 + 12155

    ∴ Current in Circuit, I =V
    R


    Correct Option: B

    In circuit, RB and RC are in series, so, Rs = 6 + 6 = 12 Ω.
    This 12 Ω resistance is in parallel with RA = 3 Ω, ​
    So, equivalent resistance of circuit

    R =3 × 12 = 36 = 12 Ω
    3 + 12155

    ∴ Current in Circuit, I =V
    R