Question 636:

• JAMB 1991

A room is heated by means of a charcoal fire, An occupant of the room standing away from the fire is warmed mainly by

A. Convection
B. Radiation
C. Conduction
D. Reflection

Question 637:

• JAMB 1991

A boy timed 30 oscillations of a certain pendulum thrice and obtained 1min. 10s, 1min. 12s and 1min. 7s respectively.The mean period of oscillation of the pendulum is

A. 0.14s
B. 0.43s
C. 2.32s
D. 6.97s

Question 638:

• JAMB 1991

Which of the following is TRUE of light and sound waves?

A. They both transmit energy
B. They both need a mediumfor propagation
C. They are both transverse waves
D. Their velocities in air are equal

Question 639:

• JAMB 1991

The image in a pin-hole camera is

A. Errect and formed by refraction through a lens
B. Virtual and formed by dispersion
C. Erect and gets sharper as the hole becomes larger
D. Inverted and formed by the light from each point travelling in a straight line

Question 640:

• JAMB 1991

When a plane mirror at which a ray is incident is rotated through an angle \( \theta \), the reflected ray will be rotated through

A. \(\frac{1}{2}\)\(\theta\)
B. \(\theta\)
C. 2\(\theta\)
D. 3\(\theta\)