A car, P, with a velocity of 30 m/s is traveling in the same direction as a car, Q, with a velocity of 20 m/s. The velocity of P relative to Q is

A converging lens and a screen are placed 20 cm and 80 cm respectively from an object in a straight line so that a sharp image of the object is formed on the screen. If the object is 3cm high. Calculate the height of the image formed

• A. 1 cm
• B. 9cm
• C. 12cm
• D. 15cm

A steam trap is a component of apparatus used in determining the specific latent heat of vaporization of steam. In the steady state, the steam trap

• A. stores the steam for future use
• B. prevents the steam from escaping
• C. ensures that only dry steam gets into the calorimeter
• D. allows condensed steam to go into the calorimeter

If a sound wave goes from a cold air region to a hot air region, its wavelength will?

• A. increase
• B. decrease
• C. decrease then increase
• D. remain constant

Calculate the gravitation force of attraction between two planets of 10²⁴kg and 10²⁷kg separated by a distance of 10²⁰meters.

• A. 6.67N
• B. 6.56N
• C. 7.5N
• D. 8.6N

In which of the following is a stationary wave produced? i. A vibrating turning fork held near the end of a resonance tube closed at one end. ii. A string tightly stretched between two points and plucked at its middle. iii. The tuning fork vibrating in air

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

When a pentavalent impurity is added to a pure semiconductor, it becomes

• A) a p-type semiconductor
• B) an n-type semiconductor
• C) an insulator
• D) an intrinsic semi-conductor

The velocity of a sound wave at 27^oC is 360ms^-1. Its velocity at 127^oC is

• A. 120?3 ms^-1
• B. 240 ms^-1
• C. 240?3 ms^-1
• D. 720?3 ms^-1

The limiting frictional force between two surface depends on

I. the gaseous reaction between the surfaces

II. the nature of the surfaces in contact

III. the relative velocity between the surfaces

• A. I only
• B. I & IV only
• C. II only
• D. III only

The conclusive test for magnetism in a steel bar suspended horizontally at its midpoint is when the bar

• A. always settles in the magnetic N-S direction.
• B. is repelled by a magnet.
• C. always settles in the magnetic E-W direction
• D. is attracted by a magnet.