(a) What is an intrinsic semiconductor?

(b) Distinguish between the p-type and n-type semi-conductors.

A piece of wire gauze can be made to lie on water because

• A. the wire guaze is less dense than water
• B. the water molecules repels the wire guaze upwards
• C. the water surface has the effect of an elastic thin skin
• D. of the cohensive forces between the water and the wire guaze molecules

(a) List two types of waves, apart from light, that can be plane polarized.

(b) State two applications of plane polarized light.

In the diagram below, the hanging mass m2 is adjusted until m1 is on the verge of sliding. The coefficient of static friction between the mass m1 and the table is

• A. m1/m2
• B. m1g/m2
• C. m2/m1
• D. m2g/m1

Total internal reflection. i. is a phenomenon of refraction of light. ii. occurs when light rays travel into a denser medium. iii. occurs when the critical angle is just exceeded. iv. is a phenomenon of reflection of light. Which of the statements above are correct?

• A. i and ii only
• B. i and iii only
• C. i, ii and iii only
• D. i, iii and iv only

A sealed flask contains 600cm³ of air at 27^°C and is heated to 35^°C at constant pressure. The new volume is?

• A) 508cm³
• B) 516cm³
• C) 608cm³
• D) 616cm³

When two objects P and Q are supplied with the same quantity of heat,the temperature change in P is observed to be twice that in Q. If the masses of P and Q are the same,calculate the ratio of the specific heat capacities of P and Q

• A. 1:1
• B. 1:3
• C. 1:4
• D. 1:2

Which of the following is a semiconductor

• A. copper
• B. silicon
• C. plastic
• D. Iron

The sound of an electricity bell dies down slowly when air is slowly pumped out from a bottle because

• A) the wavelength of sound becomes greater in the bottle
• B) sound cannot pass through the bottle
• C) sound needs a material medium
• D) sound can pass through a vacuum

Water of mass 1.5kg is heated from from 30^oC to 80^oC using an electric kettle which is rated 5A, 230V. Calculate the time taken to reach the final destination [specific heat capacity of water 4200Jkg^-1K^-1]

• A. 4.57 minutes
• B. 5.02 minutes
• C. 7.30 minutes
• D. 10.04 minutes