JAMB Physics Past Questions & Answers - Page 271

1,351.

The number of neutrons contained in the nucleus \(^{238}_{92}U\) is

A.

92

B.

146

C.

238

D.

330

Correct answer is B

238 - 92 = 146

1,352.

A 0 - 10mA galvanometer with a coil resistance of 30\(\Omega\) can be converted to a 0 - 10A ammeter by using

A.

0.03\(\Omega\) series resistor

B.

0.03\(\Omega\) shunt resistor

C.

9.99\(\Omega\) shunt resistor

D.

9.99\(\Omega\) series resistor

Correct answer is B

No explanation has been provided for this answer.

1,353.

A lamp is rated 240V, 60W. The resistance of the filament is

A.

960\(\Omega\)

B.

16\(\Omega\)

C.

15\(\Omega\)

D.

4\(\Omega\)

Correct answer is A

P = \(\frac{V_2}{R}\) \(\Rightarrow\) R = \(\frac{V_2}{p}\)

= \(\frac{240\times 240}{60}\)

= 960\(\Omega\)

1,354.

Electrical power is transmitted at a high voltage rather than low voltage because the amount of energy loss is reduced due to

A.

heat dissipation

B.

production of eddy currents

C.

excessive current discharge

D.

excessive voltage distance

Correct answer is A

No explanation has been provided for this answer.

1,355.

Which of the following is most suitable for protecting the circuit of 2000W electric iron connected to a 250V mains?

A.

13A

B.

8A

C.

5A

D.

3A

Correct answer is B

P = IV \(\Rightarrow\) I = \(\frac{2000}{250}\)

= 8A