Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion (A): In the process of photoelectric emission, all emitted electrons have the same kinetic energy.
Reason (R): According to Einstein's equation $E_k=h v-\phi_0$.

A
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

(d) A is false but R is true.
Explanation: A is false but R is true.

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MCQ 21 Mark

Assertion (A): If the frequency of the applied AC is doubled, then the power factor of a series R-L circuit decreases.
Reason (R): Power factor of series R-L circuit is given by \$\cos \phi=\frac{2 R}{R^2+\omega^2 L^2}$

A
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

(c) A is true but R is false.
Explanation: $\cos \phi=\frac{R}{Z}=\frac{R}{\sqrt{R^2+\omega^2 L^2}}$
When $\omega$ is doubled, power factor $(\cos \phi)$ decreases.
So, A is true but R is false.

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MCQ 31 Mark

Assertion (A): Two adjacent conductors of unequal dimensions, carrying the same positive charge have a potential difference between them.
Reason (R): The potential of a conductor depends upon the charge given to it.

A
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

(b) Both A and R are true but R is not the correct explanation of A.
Explanation: Both A and R are true but R is not the correct explanation of A.

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MCQ 41 Mark

Assertion (A): To observe diffraction of light, the size of the obstacle/aperture should be of the order of $10^{-7} m$.
Reason (R): $10^{-7}$ is the order of the wavelength of visible light.

A
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

(a) Both A and R are true and R is the correct explanation of A.
Explanation: Both A and R are true and R is the correct explanation of A. Diffraction is prominent when the size of the obstacle or the aperture is comparable to the wavelength of light used.

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Physics Assertion (A) & Reason (B) MCQ

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