What happens to the capacitance in variable capacitors when the plates separate?

What happens to the capacitance in variable capacitors when the plates separate?

• A. The capacitance increases
• B. The capacitance stays the same
• C. The capacitance decreases
• D. The capacitance fluctuates

Answer: (C)

Capacitance is defined by the formula \( C = \frac{\varepsilon A}{d} \), where \( C \) is capacitance, \( \varepsilon \) represents the permittivity of the dielectric material between the plates, \( A \) is the area of one of the plates, and \( d \) is the distance between the plates. When the plates of a variable capacitor are separated, the distance \( d \) increases. According to the formula, as the distance \( d \) increases, the capacitance \( C \) decreases because the area \( A \) remains constant and the permittivity \( \varepsilon \) of the dielectric does not change. This relationship shows that the larger the distance between the plates, the lower the capacitance. This decrease in capacitance due to increased plate separation is a fundamental principle of how capacitors work and is crucial in applications where variable capacitance is needed, such as tuning circuits.

Capacitance is defined by the formula ( C = \frac{\varepsilon A}{d} ), where ( C ) is capacitance, ( \varepsilon ) represents the permittivity of the dielectric material between the plates, ( A ) is the area of one of the plates, and ( d ) is the distance between the plates.

When the plates of a variable capacitor are separated, the distance ( d ) increases. According to the formula, as the distance ( d ) increases, the capacitance ( C ) decreases because the area ( A ) remains constant and the permittivity ( \varepsilon ) of the dielectric does not change. This relationship shows that the larger the distance between the plates, the lower the capacitance.

This decrease in capacitance due to increased plate separation is a fundamental principle of how capacitors work and is crucial in applications where variable capacitance is needed, such as tuning circuits.