When cold water is poured on a can containing hot water, the can collapses because the

• A) steam condeses and occupies the partial vacuum in the can
• B) external air pressure counter balances the pressure within the can
• C) steam expands to occupy the vacuum remaining in the can
• D) external pressure becomes greater than the pressure within the can.

Which of the following descriptions of the image formed by a plane mirror is not correct. the image is----

• A. erect and of the same size as the object
• B. laterally inverted and of the same size as the object
• C. erect and bigger than the object
• D. virtual and if the same size

When a paint brush is removed from clean water, the bristles of the brush are pulled together because of

• A. The viscosity of the surrounding air
• B. The low density of water
• C. Surface tension forces
• D. The weight of the brush bristles

118.8cm² surface of the copper cathode of a voltameter is to be coated with 10^-6m thick copper of density 9 x 10³kgm^-3. How long will the process run with 10A constant current?

[3.3 x 10-7kgC^-1]

• A) 5.4 min
• B) 10.8 min
• C) 15.0 min
• D) 20.0 min

The diagram below shows the wire of a sonometer box set into resonance by a vibrating tuning fork of frequency f, when the wire is stretched by a tension T, the resonating length of the wire is I while the wavelength of the sound produced is ? λ. Which of the following statements about the frequency of vibration of the wire is not correct?

• A. proportional to the mass per unit length of the wire
• B. equal to the frequency of the tuning fork
• C. inversely proportional to the length of the wire
• D. proportional to the sqare root of the tension

Name three classes of magnetic materials.

Which of the following is a characteristics of stationary waves?

• A. They are formed by two identical waves travelling in opposite directions
• B. they can be transverse or longitudinal
• C. The distance between two successive nodes is one wavelenght
• D. The antinode is a point of minimum displacement

The current I in the fig below is

• A. 4.00A
• B. 1.30A
• C. 0.80A
• D. 0.75A

Which of the following thermometers measures temperature from the thermal radiation emitted by objects?

• A. Pyrometer thermometer
• B. Platinum resistance thermometer
• C. Thermocouple thermometer
• D. Constant pressure gas thermometer