# Transfer Of Thermal Energy - Convection

10 Questions | Total Attempts: 1403

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Online Quiz - Convection

• 1.
An electrical heater is immersed in water. What is the main means in which heat is transferred from the heater to the water?
• A.

Conduction

• B.

Convection

• C.

Conduction and convection

• D.

None of the above

• 2.
Convection can occur in ___________.
• A.

Liquids only

• B.

Liquids and gases

• C.

Vacuum

• D.

Gases and solids

• 3.
The air in a large paper bag is heated. The bag is then found to rise through the surrounding cold air. This is because ________________.
• A.

The air in the bag has become less dense

• B.

The mass of the paper bag has decreased

• C.

The chemical compositions of the air in the bag has changed

• D.

The mass of the air in the bag has increased

• 4.
In a hot water tank, the heating element should be placed at the bottom because _________________.
• A.

Conduction cannot take place when the heater is at the top of the tank

• B.

The heated water will rise and form a convection current

• C.

Radiant heat travels faster in the upward direction

• D.

The heater must be covered by water at all times

• 5.
Water in a beaker is heated at X. Which diagram best shows the convection currents?
• A.

A

• B.

B

• C.

C

• D.

D

• 6.
The diagram shows a crystal being heated in a beaker of water. The crystal releases a dye which shows how the water circulates around the beaker. What is happeningto cause the water above the crystal to rise?
• A.

The water contracts and its density decreases.

• B.

The water contracts and its density increases.

• C.

The water expands and its density decreases.

• D.

The water expands and its density increases.

• 7.
In the process of convection, energy is transferred __________.
• A.

Because of density differences in a liquid

• B.

Because of temperature differences in a solid

• C.

By the diffusion of molecules through a fluid

• D.

By the vibration of molecules about a mean position

• 8.
Which of the following methods would not produce convection currents in a container filled with water at 30oC?
• A.

Lighting a candle beneath the container

• B.

Floating a piece of ice on the water

• C.

Placing a lighted bulb just above the water surface

• D.

Dropping a piece of hot metal into the water

• 9.
In very cold weather, ice can form on the surface of puddles of water because the air temperature is below that of the water. If the ice layer is found to be thickening at its lower surface, then thermal energy must be mostly _________________.
• A.

Conducted away from the ice through the air

• B.

Convected away from the ice through the water

• C.

Conducted from the upper to the lower surface of the ice

• D.

Convected towards the ice through the air

• 10.
Which statement about convection is correct?
• A.

Brownian motion is a form of convection.

• B.

Convection occurs only in gases.

• C.

Convection results from a density change.

• D.

Evaporation is a form of convection.

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