Question 746:

• JAMB 1993

Which of the following devices may be used to step up the voltage in a d.c. circuit?

A. A step-up transformer
B. A d.c. generator
C. A wattmeter
D. An induction coil

Question 747:

• JAMB 1993

The primary aim in high tension transmission is to

A. Minimize electrical energy losses due to heat production
B. Increase the rate of energy transfer by using high voltage
C. Increase the current in the wire
D. Generate electricity at high current and low voltage

Question 748:

• JAMB 1993

Determine the inductive reactance when a 30.0mH inductor with a negligible resistance is connected to a 1.3 x 10³Hz oscillator.

A. 39.0\(\Omega\)
B. 122.5\(\Omega\)
C. 245.0\(\Omega\)
D. 39000.0\(\Omega\)

Question 749:

• JAMB 1993

Which of the following statements correctly describe(s) cathode rays? i. they consist of tiny particles carrying negative electric charges. ii. they are deflected in a magnetic field but not in an electric field. iii. they consist of fast moving neutrons and deflected in an electric field.

A. I only
B. Ii only
C. I and ii only
D. Ii and iii only

Question 750:

• JAMB 1993

Natural radioactivity is the random spontaneous disintegration of the nuclei of heavy isotopes of certain elements with the emission of

A. \(\alpha\), X, and \( \beta\)
B. \(\alpha\), \(\beta\) and \(\gamma\)-rays
C. X, \(\alpha\), \(\gamma\)-ray
D. \(\alpha\), \( \beta\) and X-rays