Question

ASSERTION: Capacitor serves as a block for dc and offers an easy path to ac.
REASON: Capacitive resistance is inversely proportional to frequency.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion
C. Assertion is correct but the Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Try to understand more about AC and DC .Try to find out how the value of capacitance changes depending on the frequency of both AC and DC current.
Use the relation between Capacitive reactance with the frequency. Note that a dc has zero frequency. If the value of frequency for a dc circuit is put in the relation.

Complete answer:
• Alternating Current reverses its direction repeatedly after a certain period and it also changes its magnitude whereas Direct Current is unidirectional.
• In DC electrons move on in a forward direction but in Alternating current electrons will move both in forward and backward direction
• The frequency of AC determines the number of times of direction change. In the case of DC since it doesn’t change its direction frequency always remains zero.
• Capacitive reactance can be expressed as ${X_c} = \dfrac{1}{{2\pi fC}}$ .
• For DC when the frequency is $0$, capacitor reactance will be infinite. Thus the capacitor will not allow the flow of DC.

So both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
Hence, the correct answer is option (A).

Note: Capacitance is the amount of charge stored in the capacitor. When current flows through capacitor internal impedance will resist the flow of current which is called capacitive reactance. Relation of capacitor reactance and frequency is important. Frequency can determine the flow of current through the capacitor.