Question 406:

• JAMB 1986

Which of the following is true of sounds?

A. Sound travels faster in air at 20^oC than at 30^oC
B. The frequency of a given sound wave changes when it crosses the boundary seperating two media
C. The wavelength of a given sound wave in air decreases as the temperature increases
D. Sound waves cannot be reflected

Question 407:

• JAMB 1986

A lens of focal length 12.0cm forms an upright image three times the size of a real object. The distance between the object and the images is

A. 8.0cm
B. 16.0cm
C. 24.0cm
D. 32.0cm

Question 408:

• JAMB 1986

In which of the following arrangements is the wavelength in an increasing order?

A. Gamma rays, infra-red rays, x-rays, radiowaves
B. Gamma rays, x-rays, infra-red ray, radiowaves
C. Radiowaves, x-rays, gamma ray, infra-red rays
D. Infra-red rays, radiowaves, x-rays, gamma rays

Question 409:

• JAMB 1986

If the refractive index of glass is 1.5, what is the critical angle at the air-glass interface?

A. Sin^-1\(\frac{1}{2}\)
B. Sin^-1\(\frac{2}{3}\)
C. Sin^-1\(\frac{3}{4}\)
D. Sin^-1\(\frac{8}{9}\)

Question 410:

• JAMB 1986

A dentist obtains a linear magnification of 4 of a hole in a tooth by placing a concave mirror at a distance, of 2.0cm from the tooth. The radius of Curvature of the mirror is

A. 5.3cm
B. 3.2cm
C. 2.7cm
D. 1.6cm