A trough 12.0cm deep is filled with water of refractive index \(\frac{4}{3}\). By how much would a coin at the bottom of the trough appear to be displaced when viewed vertically from above the water surface?

• A. 3.0cm
• B. 6.0cm
• C. 9.0cm
• D. 16.0cm

(a) Explain the term resonance and give two examples

(b)(i) Describe, with the aid of a labelled diagram, an experiment to show how the frequency of the note emitted by a vibrating string depends on the length of the string.

(ii) State two precautions necessary to obtain an accurate result.

(c) A sonometer wire is plucked and it vibrates emitting a fundamental note. State the effect on the frequency of the note if the

(i) tension in the wire were made nine times as large with no change in the length of the wire;

(ii) length of the wire were doubled with no change in the tension.

A rocket is launched from the surface of the earth. If the radius of the earth is 6.4 x 10⁶m and the acceleration of free fall due to gravity is 1Oms^-1 calculate the escape velocity of the rocket.

• A. 2.53 x 10⁴ms^-1
• B. 1.13 x 10⁴ms
• C. 8.00 x 10³ms^-1
• D. 4.23 x 10³ms^-1

An incident ray is reflected normally by a plane mirror onto a screen where it forms a bright spot. The mirror and screen are parallel and 1m apart. If the mirror is rotated through 5°, calculate the displacement of the spot

• A. 8.7cm
• B. 10.0cm
• C. 15.4cm
• D. 17.6cm

I. Its velocity is constant II. No work is done on the body III. It has constant acceleration directed away from the centre IV. The centripetal force is directed towards the centre

Which combination of the above is true of a body moving with constant speed in a circular track?

• A. II and IV
• B. I and IV
• C. II and III
• D. I and III

A boy looks at the image of an object in a plane mirror. He observes two images, a main bright one and the other faint. The observed images result from?

• A. reflection only
• B. refraction only
• C. diffraction and interference
• D. reflection and refraction

On a particular hot day, the temperature is 40°C and the partial pressure of water vapor in the air is 38.8 mmHg. What is the relative humidity?

• A. 70
• B. 62
• C. 80
• D. 42

A ray from a fixed object is incident on a plane mirror at an angle of 20^o. If the mirror is rotated through 30^o by how many degree would the reflected ray rotate?

• A. 60^o
• B. 50^o
• C. 40^o
• D. 30^o

An immersion heater is rated 120W. How long does it take the heater to raise the temperature of 1.2kg of water by 15^oC. (Assuming heat lost to the surrounding is negligible. Specific heat capacity of water = 4200 Jkg^-1K^-1C)

• A. 65.0 minutes
• B. 60.0 minutes
• C. 52.5 minutes
• D. 10.5 minutes

Three identical lamps each power 100W are connected in parallel across a potential difference of 250V. Calculate the current in the circuit

• A. 7.5A
• B. 2.5A
• C. 1.2A
• D. 0.8A