JAMB Physics Past Questions & Answers - Page 289

1,441.

A 5-v battery is connected across the plates of a 2.0\(\mu\)F uncharged parallel plate capacitor. The charge on the capacitor after a long time is

A.

2.5\(\mu\)C

B.

10.0\(\mu\)C

C.

20.0\(\mu\)C

D.

50.0\(\mu\)C

Correct answer is B

Q = cv

= 2 x 10-6 x 5

= 10 x 10-6C

= 10.0\(\mu\)C

1,442.

A wire of length 15m made of a material of resistivity 1.8 x 10-6\(\Omega\)m has a resistance of 0.27\(\Omega\). Determine the area of the wire

A.

1.5 x 10-4m2

B.

1.0 x 10-4m2

C.

2.7 x 10-5m2

D.

7.3 x 10-6m2

Correct answer is B

Resistivity = \(\frac{\text {Resiatance x Area}}{length}\)

1.6 x 10-6 = \(\frac{15 \times Area}{0.27}\)

Area = 1.0 x 10-4m2

1,443.

Which of the following factors has no effect on the e.m.f. of a primary cell?

A.

temperature

B.

size of the cell

C.

nature of the plate

D.

nature of the electrolyte

Correct answer is B

No explanation has been provided for this answer.

1,444.

When an ebolite rod is rubbed with fur, it has

A.

no charge at all

B.

a negative charge

C.

a positive charge

D.

negative and positive charges

Correct answer is B

No explanation has been provided for this answer.

1,445.

Calculate the force acting on an electron of charge 1.6 x 10-19C placed in an electric field of intensity 108Vm-1

A.

1.6 x 10-11N

B.

1.6 x 10-14N

C.

1.6 x 10-16N

D.

1.0 x 10-16N

Correct answer is A

F = EQ

1.6 x 10-19 x 108

= 1.6 x 10-11N