Question 731:

• JAMB 1993

Which of the following waves can propagate through a vacuum?

A. High velocity sound waves
B. Ultrasonic waves
C. Acoustic waves
D. Infra-red waves

Question 732:

• JAMB 1993

Radio waves emitted from an antenna are picked up by a radar after reflection from an aircraft in 4 x 10^-3S. How far is the aircraft from the antenna? [c = 3 x 10⁸ms^-1 ]

A. 6.0 x 10²ms^-1
B. 1.2 x 10³km
C. 3.0 x 10³km
D. 6.0 x 10 ⁵km

Question 733:

• JAMB 1993

Which of the following expressions gives the linear magnification produced by a concave mirror of radius of curvature r, if U and V are the object and image distances respectively?

A. \(\frac{V}{r}\) - 1
B. \(\frac{2V}{r}\) - 1
C. \(\frac{U}{r}\) - 1
D. \(\frac{2U}{r}\) - 1

Question 734:

• JAMB 1993

If the focal length of a camera lens is 20cm, the distance from the film at which the lens must be set to produce a sharp image of an object 100cm away is

A. 17cm
B. 20cm
C. 25cm
D. 100cm

Question 735:

• JAMB 1993

Which of the following may be used to explain a mirage? i. layers of air near the road surface have varying refractive indices in hot weather. ii. road surfaces sometimes become good reflectors in hot weathers. iii. light from the sky can be reflected upwards after coming close to the road surface.

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