Question 326:

• JAMB 1984

A device that converts sound energy into electrical energy is

A. The horn of a motor car
B. An A.C. generator
C. A microphone
D. The telephone
E. Radio waves

Question 327:

• JAMB 1984

Which of the following i. \(\beta\)-particles ii. protons iii. neutrons iv. \(\alpha\)-particles. may be found in light nuclei?

A. I and ii
B. I and iii
C. Ii and iv
D. Ii and iii
E. I, ii and iii

Question 328:

• JAMB 1984

Radio waves have a velocity of 3 x 10⁸ms^-1. A radio station sends out a broadcast on a frequency of 800kHz. The wavelength of the broadcast is

A. 375.0m
B. 267.0m
C. 240.0m
D. 37.5m
E. 26.7m

Question 329:

• JAMB 1984

What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 kobo per kWh?

A. N0.65
B. N0.13
C. N3.90
D. N39.00
E. N234.00

Question 330:

• JAMB 1984

Which of the following statements is (are) NOT true about the emission of the photoelectrons from metallic surfaces?
i. all metallic surfaces emits the same number of photoelectrons in a given light
ii. most metallic surfaces emit the same number of photoelectrons in visible and infra-red light
iii. a metallic surface emits photoelectrons only if the frequency of the incident light is higher than its own characteristics threshold frequency

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