PRACTICE

Which of the following is an example of a transverse and a longitudinal wave respectively?

• light and water ripples

• electromagnetic and sound

• water ripples and electromagnetic

• light and electromagnetic

The diagram shows a thick copper plate that is very hot. One side is black, the other is shiny. A student places her hands the same distance from each side as shown. Her left hand feels warmer than her right hand. Which statement is the correct conclusion from the experiment.

• The black side is hotter than the shiny one.

• The black side radiates more heat.

• The shiny side radiates more heat.

• The shiny side is cooling down faster than the black side.

The ice cubes are taken from a deep-freeeze and placed in a metal container. The container is heated at a constant rate and readings of temperature and time are taken. The results are recorded on a graph. Which temperature corresponds to 0°C?

• A

• B

• C

• D

In a vacuum flask, which methods of heat transfer are prevented by the vacuum?

• conduction only

• convection only

• conduction and convection only

• conduction, convection, and radiation

Which of the following is NOT a difference between boiling and evaporation?

• Evaporation is a slow process but boiling is a fast process.

• Evaporation takes place at the surface of the liquid but boiling takes place throughout the liquid.

• Evaporation takes place from 0°C to 100°C but boiling takes place only at the boiling point.

• During boiling, bubbles are formed but not during evaporation.

A substance that is originally a solid is heated strongly for some time. At one stage, the energy given to the substance is used as latent heat of vaporization to turn it into vapor. At this stage, what change does the energy cause?

• It breaks the bonds holding the molecules together. Molecules escape from the liquid.

• It breaks the bonds holding the molecules together. The solid becomes liquid.

• It makes the molecules move faster but there is still a strong attraction between them.

• It makes the molecules move faster and so the temperature rises.

A substance is heated in an enclosed space until it becomes a gas. After the heater is removed, the temperature is recorded at a regular intervals. The graph shows temperature plotted against time. What does the section PQ represents?

• boiling

• condensing

• melting

• solidifying

The diagram shows a graph of wave motion. Which quantities are shown by distance P and Q?

• P is the amplitude, Q is the period

• P is the amplitude, Q is the wavelength

• P is the half the amplitude, Q is the period

• P is half the amplitude, Q is the wavelength

A liquid evaporates rapidly. Why does this cause it to cool?

• Air molecules remove heat by contact with the liquid surface.

• Energy is lost by convection currents.

• Some of the most energetic molecules leave the liquid.

• The molecules have less room to move around.

A puddle of water is formed after a rain shower on a windy day. Which statement explains the effect of the wind on the rate of evaporation of the water in the puddle?

• The wind gives molecules in the water extra kinetic energy and so increases the rate of evaporation.

• The wind removes evaporated water from near the surface and so decreases the rate of evaporation.

• The wind removes evaporated water from near the surface and so increases the rate of evaporation.

• The wind takes energy from molecules near the surface and so decreases the rate of evaporation.