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Units and Measurements question

2025 · 28 Jan · Shift 2 · Q64
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Units and Measurements question

2025 · 28 Jan · Shift 2 · Q64

JEE MainPhysicsUnits and MeasurementsMCQ+4 / −1

Match List - I with List - II.

List - I List - II
(A) Angular Impulse (I) M0 L2 T-2
(B) Latent Heat (II) M L2 T-3 A-1
(C) Electrical resistivity (III) M L2 T-1
(D) Electromotive force (IV) M L3 T-3 A-2

Choose the correct answer from the options given below:

  1. A
    (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
  2. B
    (A)-(I), (B)-(III), (C)-(IV), (D)-(II)
  3. C
    (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
  4. D
    (A)-(III), (B)-(I), (C)-(II), (D)-(IV)
View written solutionFree

Correct answer: C

  1. Find dimensions of each quantity in List-I

    We match each physical quantity with its dimensional formula.

  2. (A) Angular Impulse

    Angular impulse = torque ×\times× time.

    Torque has dimensions: [τ]=[force] [distance]=(MLT−2)(L)=ML2T−2[\tau] = [\text{force}]\,[\text{distance}] = (MLT^{-2})(L) = ML^2T^{-2}[τ]=[force][distance]=(MLT−2)(L)=ML2T−2

    Therefore, [angular impulse]=ML2T−2×T=ML2T−1[\text{angular impulse}] = ML^2T^{-2}\times T = ML^2T^{-1}[angular impulse]=ML2T−2×T=ML2T−1

    So, (A)→(III)\boxed{(A) \to (III)}(A)→(III)​

  3. (B) Latent Heat

    Latent heat here means heat energy required per unit mass.

    Heat (energy) has dimensions: [Q]=ML2T−2[Q] = ML^2T^{-2}[Q]=ML2T−2

    Hence latent heat (specific latent heat): [L]=ML2T−2M=L2T−2=M0L2T−2[L] = \frac{ML^2T^{-2}}{M} = L^2T^{-2} = M^0L^2T^{-2}[L]=MML2T−2​=L2T−2=M0L2T−2

    So, (B)→(I)\boxed{(B) \to (I)}(B)→(I)​

  4. (C) Electrical resistivity

    Resistivity ρ\rhoρ is given by: ρ=RAl\rho = R\frac{A}{l}ρ=RlA​

    Resistance: R=VIR = \frac{V}{I}R=IV​

    Potential difference has dimensions: [V]=workcharge=ML2T−2AT=ML2T−3A−1[V] = \frac{\text{work}}{\text{charge}} = \frac{ML^2T^{-2}}{AT} = ML^2T^{-3}A^{-1}[V]=chargework​=ATML2T−2​=ML2T−3A−1

    Therefore, [R]=ML2T−3A−1A=ML2T−3A−2[R] = \frac{ML^2T^{-3}A^{-1}}{A} = ML^2T^{-3}A^{-2}[R]=AML2T−3A−1​=ML2T−3A−2

    Now, [ρ]=[R]L2L=(ML2T−3A−2)(L)=ML3T−3A−2[\rho] = [R]\frac{L^2}{L} = (ML^2T^{-3}A^{-2})(L) = ML^3T^{-3}A^{-2}[ρ]=[R]LL2​=(ML2T−3A−2)(L)=ML3T−3A−2

    So, (C)→(IV)\boxed{(C) \to (IV)}(C)→(IV)​

  5. (D) Electromotive force

    Electromotive force has same dimensions as potential difference: [emf]=ML2T−3A−1[\text{emf}] = ML^2T^{-3}A^{-1}[emf]=ML2T−3A−1

    So, (D)→(II)\boxed{(D) \to (II)}(D)→(II)​

  6. Final matching

    (A)→(III),(B)→(I),(C)→(IV),(D)→(II)(A)\to(III),\quad (B)\to(I),\quad (C)\to(IV),\quad (D)\to(II)(A)→(III),(B)→(I),(C)→(IV),(D)→(II)

    This corresponds to Option C.

  7. Comparison with stored answer

    Stored correct answer = C

    Our derived answer = C

    Hence, they agree.

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