Step 1: Use the formula for capacitance of a parallel plate capacitor
The capacitance \( C \) of a parallel plate capacitor with a dielectric material is given by:
\[
C = C_0 \times K
\]
where:
- \( C_0 \) is the capacitance without the dielectric (initial capacitance),
- \( K \) is the dielectric constant.
Step 2: Substitute the given values
We are given:
- Initial capacitance \( C_0 = 4 \, \mu\text{F} \),
- Dielectric constant \( K = 5 \).
Substitute these values into the formula:
\[
C = 4 \, \mu\text{F} \times 5 = 20 \, \mu\text{F}
\]
Answer: Therefore, the new capacitance is \( 20 \, \mu\text{F} \). So, the correct answer is option (1).