TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

CHAPTER 3: CAPACITANCE

MAC 2013

1. A storage capacitor has a capacitance of 65 µF. if the capacitor is charged to 4.5

V, calculate the amount of excess electrons on its negative plate.

2. The capacitance of an empty capacitor is 1.2 µF. The capacitor is connected to a

12 V battery and charged up. With the capacitor connected to the battery, a slab of

dielectric material is inserted between the plates. As a result, 2.6 x 10-5

C of

additional charge flows from one plate through the battery, and onto the other

plate. Calculate:

a. the dielectric constant of the material

b. the energy stored in the capacitor

c. the electric field between the plate if the separation between the plate is 2 mm.

OCT 2012

3. A parallel plate capacitor has a capacitance of 5.78 µF and an area of 257 m2.

a. Calculate the distance between the plates?

b. If a voltage of 89 V is applied to the capacitor, evaluate the amount of charge

collected on each plate?

c. How much work is needed to move an additional charge of 1.76 x 10-8

C from

the negative to the positive plate?

MAC 2012

4. Suppose in Figure 1 that C1 = C2 = C3 = 16.0 µF and C4 = 28.5 µF. If the charge

on C2 is Q2 = 12.4 µC, determine the charge on each of the other capacitors, the

voltage across each capacitor, and the voltage Vab, across the entire combination.

Figure 1

APR 2011

5. Define the capacitance of a capacitor

TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

6. A parallel-plate capacitor placed in vacuum has a plates separation of 5.0 mm and

area of 2.0 m2. A potential difference of 15 kV is applied across the capacitor.

Calculate:

a. Its capacitance

b. The charge on each plate

c. The magnitude of the electric field between the plates

7. The circuit in Figure 2 shows capacitors being connected across a 120 V source.

Figure 2

Calculate:

a. its equivalent capacitance

b. the voltage across the 2 nF capacitor

OCT 2010

8. A parallel plate capacitor filled with a dielectric with k = 4 is connected across a

250 V source. The plates have area of 100 cm2 and separated by a 10 mm

dielectric. Calculate

a. Its capacitance

b. The charge on the capacitor

c. The energy stored in capacitor

d. The electric filed strength between the plates

e. The new capacitance if the dielectric is removed

APR 2010

9. The equivalent capacitance of two capacitors is 35.0 µF when connected in

parallel and is equivalent to 4.0 µF when they are in series. What is the individual

capacitance of each capacitor?

10. a. How much energy must a 12 V battery expand to fully charge a 0.15 µF and a

0.20 µF capacitor when they are placed in parallel?

b. How much charge flowed from the battery in this connection?

TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

OCT 2009

Figure 3

11. Figure 3 shows a parallel plate capacitor with plate surface area of A, distance of

separation of d, and an applied voltage of V.

a. If the dielectric constant is r, write the appropriate equation and the units used

for

i. Its capacitance, C

ii. Its electric field, E between the parallel plates

b. A parallel plate capacitor has a surface dimension of 20.0 cm x 15.0 cm. the

capacitor is connected to a dc power supply of 25.0 V and a material with ɛr =

300 is inserted in between the plates. If the capacitance of the capacitor is 12.5

µF, find

i. The plates separation, d in meter

ii. The energy density of this capacitor, u in Joule per cubic meter

APR 2009

12. A parallel-plate capacitor consists of two plates, each has an area of 24 cm2

and

separated by 0.4 mm of air. The capacitor is then connected with a 12 V voltage

source. Compute,

a. The capacitance of the capacitor

b. The charge in the capacitor

c. Magnitude of the electric field in the space between the plates

13. Three capacitors are connected as shown in Figure 4. calculate

a. The equivalent capacitance across AB

b. The charge in C3 if the potential difference across AB is 6V.

TUTORIAL PHY150/Z S Mahmud/JUNE-OCT2015

Figure 4

OCT 2008

14. Figure 5 below shows three capacitors, d C2 and C3. Find

a. The equivalent capacitance

b. Potential different across them

c. Charges on d, C2 and C3

Figure 5