Q1. When the air between the plates of a capacitor is replaced by mica of dielectric constant 4, its capacitance:
A remains unaffected
B reduces to 1/4th
C becomes 4 times Correct
D becomes 2 times
Explanation
For a parallel-plate capacitor, inserting a dielectric fully between the plates multiplies the original capacitance by the dielectric constant. Air is taken approximately as having dielectric constant 1, while mica is given here as having dielectric constant 4. Therefore, the new capacitance becomes four times the earlier value. It does not remain unchanged, because the medium between the plates has changed. It does not reduce to one-fourth; that would be the reverse of the dielectric effect. It also does not merely double, because the given dielectric constant is 4, not 2.