Question

A parallel plate capacitor of capacitance 100 pF is to be constructed by using paper sheets of 1 mm thickness as dielectric. If the dielectric constant of paper is 4, the number of circular metal foils of diameter 2 cm each required for the purpose is

• A. 40
• B. 20
• C. 30
• D. 10

Hint:

To find the number of plates, first calculate the area and required capacitance, then divide by the capacitance per plate.

Answer 1

The Correct Option is D

Step 1: Formula for capacitance of parallel plate capacitor.
The capacitance of a parallel plate capacitor is given by: \[ C = \frac{\epsilon A}{d} \] where \( \epsilon \) is the dielectric constant, \( A \) is the area of one plate, and \( d \) is the separation between plates. Given the dielectric constant and thickness, we can calculate the number of plates required.

Step 2: Conclusion.
Hence, the number of plates required is 10, so the correct answer is option (D).

Final Answer: \[ \boxed{10} \]