11. Which is the correct expression for the capacitance of a multi-plate capacitor?
A. C = absolute permittivity × A/d
B. C = Actual permittivity × (n-1) × A/d
C. C = Actual permittivity × (n) × A/d
D. Actual permittivity × (n+1) × A/d
Answer: B
The correct expression for capacitance of a multi plate capacitor is
C = Actual permittivity × (n-1) × A/d.
Where
n = number of plates
A = area of cross section of the plates
d = distance of separation between the plates.
12. What happens to the capacitance of a multi-plate capacitor when the area of a cross-section of the plate decreases?
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: B
When the area of the cross-section decreases, the capacitance also decreases since it is related to the formula
C = Actual permittivity × (n-1) × A/d.
Here, we can see that the capacitance is directly proportional to the area of the cross-section.
13. What happens to the capacitance of a multi-plate capacitor when the distance of separation between the plate increases?
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: B
When the distance of separation between the plates increases, the capacitance decreases since it is related to the formula
C = Actual permittivity × (n-1) × A/d.
Here, we can see that the capacitance is inversely proportional to the distance of separation.
14. What happens to the capacitance of a multi-plate capacitor when the number of plates increases?
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: A
When the number of capacitors increases, the capacitance also increases since it is related to the formula
C = Actual permittivity × (n-1) × A/d.
Here, we can see that the capacitance is directly proportional to the number of capacitors.
15. Find the capacitance of a multi-plate capacitor whose actual permittivity = 5F/m, n = 3, A = 4m2and d = 2m.
A. 10F
B. 20F
C. 30F
D. 40F
Answer: B
The formula for capacitance of a multi plate capacitor
C = Actual permittivity × (n-1) × A/d.
Thus, C = 5 × (3-1) × 4/2 = 20F.
16. Find the capacitance of a multi-plate capacitor whose relative permittivity = 5, n = 3, A = 4m2 and d = 2m.
A. 1.77 × 10-10 F
B. 1.77 × 1010 F
C. 1.77 × 10-11 F
D. 1.77 × 1011 F
Answer: A
The formula for capacitance of a multi plate capacitor