Units & Measurements

JEE Physics · 184 questions · Page 19 of 19 · Click an option or "Show Solution" to reveal answer

Q181

Let

\ell

, r, C and V represent inductance, resistance, capacitance and voltage, respectively. The dimension of

{\ell \over {rCV}}

in SI units will be :

A [A–1]

B [LTA]

C [LA–2]

D [LT2]

Correct Answer

Option A

Solution

\left[ {{\ell \over r}} \right] =

T [CV] $=$ AT So,

\left[ {{\ell \over {rCV}}} \right]

{T \over {AT}}

= [A $-$ 1]

Q182

An example of a perfect diamagnet is a superconductor. This implies that when a superconductor is put in a magnetic field of intensity B, the magnetic field Bs inside the superconductor will be such that :

A Bs =

-

B Bs = 0

C Bs = B

D Bs < B but Bs

\ne

Correct Answer

Option B

Solution

Key Concept: In a superconductor below its critical temperature, the Meissner effect occurs → it completely expels magnetic flux from its interior.

This means the magnetic induction inside the superconductor is: $B_s = 0$ regardless of the applied external field (until the critical field strength is exceeded).

Correct Option: Option B: $B_s = 0$ ✅

Q183

Match (Experiment performed) with (Phenomena discovered/associated) and select the correct option from the options given below the lists : .tg .tg

List - I		List - II
(a)	Davisson and Germer Experiment	(i)	Wave nature of electrons
(b)	Millikan’s oil drop experiment	(ii)	Charge of an electron
(c)	Rutherford experiment	(iii)	Quantisation of energy levels
(d)	Franck - Hertz experiment	(iv)	Existence of nucleus

A (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)

B (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)

C (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

D (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

Correct Answer

Option B

Solution

Let’s carefully match them: (a) Davisson and Germer Experiment → Demonstrated wave nature of electrons via electron diffraction. → (i) (b) Millikan’s Oil Drop Experiment → Measured charge of an electron. → (ii) (c) Rutherford Experiment → Showed the existence of nucleus in the atom through alpha-particle scattering. → (iv) (d) Franck–Hertz Experiment → Demonstrated quantisation of energy levels in atoms (mercury). → (iii) So correct matching is: (a)-(i), (b)-(ii), (c)-(iv), (d)-(iii) ✅ Answer: Option B

Q184

The pair of physical quantities not having the same dimensions is :

A Angular momentum and Planck's constant

B Torque and energy

C Surface tension and impulse

D Pressure and Young's modulus

Correct Answer

Option C

Solution

\begin{aligned} & {[\tau]=[\mathrm{E}]} \\ & {[\sigma] \neq[\mathrm{I}]} \\ & {[\mathrm{L}]=[\mathrm{h}]} \\ & {[\mathrm{P}]=[\mathrm{Y}]} \end{aligned}

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