IGCSE Physics MCQs 11 - Thermal Energy Transfers

Why are metals better thermal conductors than other solids?

• Metals contain free electrons which help transfer energy.

• Molecules in metals are in fixed positions.

• Molecules in metals can move freely.

• Molecules in metals vibrate faster than those in other solids.

Two freezers X and Y are identical except that one has a door opening at the front and the other has a door opening at the top.

Both doors are the same size and are opened for the same amount of time.

Which freezer gains the least amount of thermal energy in this time and why?

• Freezer: X | Reason: cold air falls

• Freezer: X | Reason: warm air falls

• Freezer: Y | Reason: cold air falls

• Freezer: Y | Reason: warm air falls

The diagram shows a vacuum flask used to keep a liquid warm.

Which methods of heat loss are reduced by the vacuum between the silvered walls?

• conduction only

• conduction and convection only

• convection and radiation only

• conduction, convection, and radiation

In countries where it is usually hot, houses are often painted white.

What is the reason for this?

• White surfaces are good reflectors of radiant energy.

• White surfaces are good transmitters of radiant energy.

• White surfaces are good absorbers of radiant energy.

• White surfaces are good emitters of radiant energy.

Which method of thermal transfer occurs when the density of some of a liquid decreases and the liquid moves upwards?

• conduction

• convection

• evaporation

• radiation

The diagram shows a tent made from a new material.

What type of material should the tent be made of to reflect the radiant energy from the Sun?

• Texture: dull | Colour: black

• Texture: dull | Colour: white

• Texture: shiny | Colour: black

• Texture: shiny | Colour: white

A beaker contains some cold water. A purple crystal is placed on the bottom of the beaker. The beaker is gently heated beneath the crystal. The crystal dissolves in the water. The colour spreads, as shown in the diagram.

Three students each make a statement about the experiment.

Studen 1 says the purple water is less dense than the rest of the water.

Student 2 says the purple water is warmer than the rest of the water.

Student 3 says all of the water will eventually get heated, even though water is a poor conductor of thermal energy.

Which students are correct?

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

• 1, 2, and 3

A surface is made so that it is a good source of infrared radiation.

Which surface is NOT suitable?

• a surface that is painted matt black

• a surface that is painted white

• a surface that is heated to a high temperature

• a surface that has a large surface area

In a cold country, the ground is covered in snow. There is a pile of black sand outdoors and its temperature is the same as that of the snow. A man sprinkles a thin layer of this sand over the snow.

Why does the black sand help to melt the snow during the day?

• Any thermal energy still left in the sand will melt the snow.

• The black sand is a good absorber of the infrared radiation from the Sun.

• The black sand is a good conductor of thermal energy.

• The black sand lowers the melting point of the snow.

A sealed metal box contains a fixed mass of air. The sides of the box are insulated.

A scientist investigates the thermal conductivity of air. She measures how quickly thermal energy passes between the top and bottom of the box.

Which row gives the correct procedure and conclusion?

• Procedure: heat bottom surface | Conclusion: air is a good thermal conductor

• Procedure: heat bottom surface | Conclusion: air is a poor thermal conductor

• Procedure: heat top surface | Conclusion: air is a good thermal conductor

• Procedure: heat top surface | Conclusion: air is a poor thermal conductor