KFUPM-Physics102-052

Dr.Aljalal

Sec16

Sec17

Sec18

Recitation ch 25

Answers at the end

Question 1

Two capacitors, C1 and C2, are connected in series and a

potential difference is applied to the combination. If the

capacitor that is equivalent to the combination has the same

potential difference, then the charge on the equivalent

capacitors is the same as:

a The ratio of the charges on C1 and C2.

b The sum of the charges on C1 and C2.

c The charge on C1 or C2.

d The difference of the charges on C1 and C2.

e The product of the charges on C1 and C2.

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Question 2

Capacitor C1 has a capacitance of 4 micro-Farad.

It is charged using a 100-volt battery. The battery

is disconnected. Then, C1 is connected in parallel

to another uncharged capacitor C2. Now, the potential

difference between the plates of each capacitor is 40 V.

What is the value of C2 ?

a 2 micro-Farad

b 10 micro-Farad

c 4 micro-Farad

d 6 micro-Farad

e 8 micro-Farad

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Question 3

In figure (8), find the total charge stored by the three

capacitors if the potential difference “V” is 10.0 volts.

Assume C1 = 10.0 micro-F, C2 = 5.00 micro-F and

C3 = 4.00 micro-F.

a 26.1 micro-C.

b 61.3 micro-C.

c 22.1 micro-C.

d 31.6 micro-C.

e 63.4 micro-C.

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Question 4

Capacitors A and B are identical. Capacitor A is charged so

it stores 4 J of energy and capacitor B is uncharged. The

capacitors are then connected in parallel. The total stored

energy in the capacitors is now:

a 16 Joules.

b 2 Joules.

c 4 Joules.

d 1 Joules.

e 8 Joules.

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Question 5

In figure 6: V = 100 V, C1 = 10.0, C2 = 5.00, C3 = 4.00.

All capacitor values are in microFarads.

What is the energy stored in C1 ?

a 50.0 mJ

b 5.56 mJ

c 1.12 mJ

d 11.2 mJ

e 10.3 mJ

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Question 6

The space between the plates of a 2.0-nanoFarad parallel-plate

capacitor is completely filled with a dielectric of dielectric

constant k = 5. A battery is used to charge the capacitor to a

potential difference of 100 V. Then the battery is disconnected

and the dielectric is pulled completely out of the capacitor.

What is the final energy stored in the capacitor ?

a 1.0*10**(-5) J

b 5.0*10**(-5) J

c 0.2*10**(-5) J

d 0.5*10**(-5) J

e 2.0*10**(-5) J

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Question 7

A 2 micro-F and a 1 micro-F capacitor are connected in series

and a potential difference is applied across the combination.

The 2 micro-F capacitor has:

a half the charge of the 1 micro-F capacitor.

b zero of stored energy.

c twice the potential difference of the 1 micro-F capacitor.

d twice the charge of the 1 micro-F capacitor.

e half the potential difference of the 1 micro-F capacitor.

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Question 8

A parallel-plate capacitor has a plate area of 0.2 m**2 and

a plate separation of 0.1 mm. If the charge on each plate has

a magnitude of 4.0*10**(-6) C the electric field between the

plates is approximately:

a Zero.

b 1.4*10**4 V/m.

c 9.2*10**3 V/m.

d 2.3*10**6 V/m.

e 4.2*10**6 V/m.

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Question 9

A parallel plate capacitor has a plate area of 0.2 m**2

and a plate separation of 0.1 mm. The charge on each

plate is 4.0 microCoulombs.

What is the electric field between the plates ?

a 1.0*10**6 V/m

b zero

c 4.0*10**2 V/m

d 2.3*10**6 V/m

e 4.0*10**12 V/m

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Question 10

In figure 7, C1 = 12 micro-Farads, C2 = 6 micro-Farads

and C3 = 20 micro-Farads.

What is the total energy stored by the capacitors ?

a 88.4 mJ

b 0.981 mJ

c 0.100 mJ

d 30.4 mJ

e 0.491 mJ

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Question 11

An air filled parallel-plate capacitor has a capacitance of

1.00*10**(-12) F. The plate separation is then doubled and a

wax dielectric is inserted, completely filling the space

between the plates. As a result the, capacitance becomes

2.00*10**(-12) F. The dielectric constant of the wax is:

a 4.00.

b 8.00.

c 0.25.

d 2.00.

e 0.50.

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Question 12

Find the equivalent capacitance of three capacitors

connected in series. Assume the three capacitors are:

C1 = 2.00 micro-F, C2 = 4.00 micro-F and

C3 = 8.00 micro-F.

a 15.4 micro-F.

b 26.1 micro-F.

c 3.01 micro-F.

d 1.14 micro-F.

e 0.88 micro-F.

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Question 13

Figure 5 shows six capacitors each having a capacitance

of 6-microFarad.

The capacitance between points a and b is:

a 3 microFarad

b 1 microFarad

c 6 microFarad

d 4 microFarad

e 9 microFarad

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Question 14

A battery is used to charge a parallel-plate capacitor.

The battery is disconnected, and then, the plates are

pulled apart to twice their original separation.

This process will double the :

a surface charge density on each plate

b electric field between the plates

c capacitance

d stored energy

e charge on each plate

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Question 15

The potential difference between the plates of an

isolated, charged capacitor is Vo. A slab of dielectric

material is inserted filling completely the space between

the plates. The potential difference across the capacitor

is now Vo/2. Find the dielectric constant of the material.

a 0.5

b 16

c 2

d 8

e 4

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Answers

1 c

2 d

3 d

4 b

5 b

6 b

7 e

8 d

9 d

10 d

11 a

12 d

13 d

14 d

15 c