Jamb Physics 1985 Past Questions and Answers

Question 26:

• JAMB 1985

In order to find the depth of the sea, a ship sends out a sound wave and receives an echo after one second. If the velocity of sound in water is 1500ms^-1, what is the depth of the sea?

A. 0.75km
B. 1.50km
C. 2.20km
D. 3.00km
E. 3.75km

Question 27:

• JAMB 1985

When a sound wave passes from air into water its

A. Speed and frequency increases but its wavelength remains the same
B. Speed and wavelength increases but its frequency remains the same
C. Speed decreases
D. Speed remains the same but its frequency and wavelength change
E. Speed increases but its frequency and wavelength decreases

Question 28:

• JAMB 1985

If the fundamental frequency of a closed pipe organ on a day when the speed of sound is 340ms^-1 is 170Hz, then the length of the pipe is

A. 50cm
B. 70cm
C. 100cm
D. 150cm
E. 200cm

Question 29:

• JAMB 1985

An object is placed 15cm in front of a concave mirror of radius 40cm. The image formed

A. Virtual and 60cm behind the mirror
B. Real and 60cm behind the mirror
C. Virtual and at infinity
D. Real and at infinity
E. Virtual and 40cm from the mirror

Question 30:

• JAMB 1985

A 45^o triangular glass prism can be used as a reflector of light because

A. A refraction never takes place in such a prism
B. The angle of reflection equals the angle of incidence
C. The refractive index of glass is less than 1
D. It is transparent
E. The critival angle angle for glass is less than 45^o