Physical World, Units and Measurements


  1. Dimensions of resistance in an electrical circuit, in terms of dimension of mass M, of length L, of time T and of current I, would be​









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    Dimensions of Resistance, =
    [V]
    =
    [ML2T-3I-1]
    = [ML2T-3I-2]
    [I][I]

    Correct Option: C

    Dimensions of Resistance, =
    [V]
    =
    [ML2T-3I-1]
    = [ML2T-3I-2]
    [I][I]


  1. The dimensions of universal gravitational constant are​​​









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    F =
    G M1m1
    ⇒ G =
    F r2
    r2M1m1

    ∴ dimension of G is
    MLT-2 [L2]
    = M-1L3T-2
    [M] [M]

    Correct Option: B

    F =
    G M1m1
    ⇒ G =
    F r2
    r2M1m1

    ∴ dimension of G is
    MLT-2 [L2]
    = M-1L3T-2
    [M] [M]



  1. Which one of the following groups have quantities that do not have the same dimensions?​​









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    Force has dimension [MLT – 2] while impulse has dimension [MLT – 1], both have different dimensions.

    Correct Option: C

    Force has dimension [MLT – 2] while impulse has dimension [MLT – 1], both have different dimensions.


  1. The dimensions of Planck’s constant are same as ​​









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    We know that E = hυ

    h =
    E
    =
    [ML2T-2]
    = [ML2T-1]
    υ[T-1]

    Angular momentum = Iω ​
    = [ML2][T – 1] = [ML2T – 1]

    Correct Option: D

    We know that E = hυ

    h =
    E
    =
    [ML2T-2]
    = [ML2T-1]
    υ[T-1]

    Angular momentum = Iω ​
    = [ML2][T – 1] = [ML2T – 1]



  1. The pair of quantities having same dimensions is​​









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    Work = Force ×  displacement ​
    Torque = Force × force arm ​ 
    = mass × acceleration × length ​ 
    = [M] × [LT – 2] × [L] = [M L2T – 2]

    Correct Option: D

    Work = Force ×  displacement ​
    Torque = Force × force arm ​ 
    = mass × acceleration × length ​ 
    = [M] × [LT – 2] × [L] = [M L2T – 2]