| Directions: In the following questions, a statement of Assertion [A] is followed by a statement of Reason (R). |
| Mark the correct choice as: |
| Assertion [A]: An electric lamp connected in series with a variable capacitor and AC source, its brightness increases with increase in capacitance. |
| Reason (R): Capacitive reactance decreases with increase in capacitance of capacitor. |
A) Both Assertion [A] and Reason (R) are true and Reason (R) is the correct explanation of Assertion [A]
B) Both Assertion [A] and Reason (R) are true but Reason (R) is not the correct explanation of Assertion [A]
C) Assertion [A] is true but Reason (R) is false
D) Assertion [A] is false and Reason (R) is also false
Correct Answer: A
Solution :
(a) Capacitive reactance \[{{X}_{C}}=\frac{1}{\omega C}\] when capacitance (C) increases, the capacitive reactance decreases due to decrease in its values, the current in the circuit will increase \[\left( l=\frac{E}{\sqrt{{{R}^{2}}+X_{C}^{2}}} \right)\] and hence brightness of source (electric lamp) will also increase.
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