Question 41:

• JAMB 1978

The boys are communicating with each other by stretching a string passing through a hole punched in the bottom of each of two tin cans. The physical principle employed is that sound travels

A. Mainly through air
B. Fainter in stretched string
C. Faster through gases than in solids and liquids
D. With greater ease through a string than in air
E. None of the above is correct

Question 42:

• JAMB 1978

A herdsman yelling out to fellow herdsman heard his voice reflected by cliff 4s later. What is the velocity of sound in air if the cliff is 680m away?

A. 170ms^-1
B. 136ms^-1
C. 340ms^-1
D. 680ms^-1
E. 510ms^-1

Question 43:

• JAMB 1978

an object 1cm high placed on the axis 15cm from a converging lens forms an image 30cm from the lens. The size of the image is

A. 0.5cm
B. 1.5cm
C. 3cm
D. 2.5m
E. 2cm

Question 44:

• JAMB 1978

The visible part of light consists of the following colours

A. Red, indigo, infra-red, violet, yellow, green and blue
B. Red, green, blue, violet, indigo, orange and yellow
C. Blue, ultra-violet, infra-red, red, yellow, indigo, violet,green and orange
D. Infra-red and ultra-violet
E. Red, orange, yellow, green, blue, indigo and infra-red

Question 45:

• JAMB 1978

An object is positioned between two plane mirrors inclined at right angles to each other. The object is 1 unit distance from each mirror, the number of images formed is

A. 1
B. 2
C. 3
D. 4
E. 5