Question

A variable parallel plate capacitor and an electroscope are connected in parallel to a battery. The reading of the electroscope would be decreased by

• A. increasing the area of overlap of the plates
• B. placing a block of paraffin wax between the plates
• C. decreasing the distance between the plates
• D. decreasing the battery potential

Answer 1

Answer: (D)

decreasing the battery potential

The electroscope reading depends on the charge present on the capacitor which depends on its capacitance and the potential across it.
Now, increasing the area of plates or decreasing the distance between them increases the capacitance which increases the charge.
Introducing a dielectric also increases the capacitance increasing the charge.
However, decreasing the potential decreases the charge decreasing the electroscope reading.