JAMB Physics Past Questions & Answers - Page 265

1,321.

What precaution should a manufacturer take to ensure that energy loss in a transformer is minimized?

A.

the winding of the transformer should be made of high resistance wire

B.

the core should be made of thin sheets of metal

C.

the core should be made of thin sheets of metal

D.

the flux linking the primary with the secondary coils should be minimum

Correct answer is B

No explanation has been provided for this answer.

1,322.

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

1,323.

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.

1,324.

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\(\Omega\)

1,325.

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.