A rocket burns fuel at the rate of 10kgs^-1 and ejects it with velocity of 5 x 10³ms^-1. The thrust exerted by the gas on the rock is

• A. 2.5 x 10⁷N
• B. 5.0 x 10⁴N
• C. 5.0 x 10²N
• D. 2.0 x 10^-3N

A listener can detect the instrument from which a note is being sounded because different instruments produce the same note with a different.

• A. frequencies
• B. pitches
• C. loudness
• D. overtones

Shadows and eclipses result from the

• A. refraction of light
• B. rectilinear propagation of light
• C. defraction of light
• D. reflection of light

The amplitude of a wave is the

• A. distance between two successive troughs of the wave
• B. separation of two adjacent particles vibrating in phase
• C. maximum displacement of the wave particle from the equilibrium position
• D. distance travelled by a wave in a complete cycle of its motion

The pinhole camera works on

• A. the principle of the reversibility of light
• B. the principle of the rectilinear propagation of light
• C. Huygen
• D. the principle of total internal reflection of light

State three observable phenomena where a particle behaves like waves. State the scientific principle underlying the operation of fibre optics.

(b) Explain each of the following terms as used in fibre optics: (i) core; (ii) cladding

(a) Define critical angle.

(b) How are anti-nodes created in a stationary wave?

(c) The angle of minimum deviation of an equilateral triangular glass prism is 46.2°. Calculate the refractive index of the glass.

(d) An illuminated object is placed in front of a concave mirror and the position of a screen is adjusted in front of the mirror but no image is obtained on the screen. Give two possible reasons for this observation.

(e) An illuminated object is placed at a distance of 75 cm from a converging lens of focal length 30 cm.

(i) Determine the image distance.

(ii) If the lens is replaced by another converging lens, the object has to be moved 25 cm further away to have its sharp image on the screen. Determine the focal length of the second lens.

A wire, 20m long is heated from a temperature of 5°C to 55°C. If the change in length is 0.020m, calculate the linear expansivity of the wire

• A. 1.0 x 10^-3k^-1
• B. 2.0 x 10^-4k^-1
• C. 2.0 x 10^-5k^-1
• D. 1.0 x 10^-5k^-1

Borh's theory provides evidence for the

• A. structure of the atom
• B. positive charge of an electron
• C. existence of energy level in the atom
• D. positive charge on a proton

In a thermonuclear reaction, the total initial mass is 5.02 x 10^−27kg and the total final mass is 5.01 x 10^−27kg. The energy released in the process is [c = 3.0 x 10⁸ ms^-1]

• A. 9.0 x 10-13J
• B. 9.0 x 10-12J
• C. 9.0 x 10-11J
• D. 9.0 x 10-10J