Convection and Convection Currents

What is convection?

• Transfer of heat through the movement of a fluid

• Transfer of heat through conduction

• Transfer of heat through radiation

• Transfer of heat through the movement of a solid

Explain how temperature difference affects convection.

• Temperature difference has no effect on convection.

• Temperature difference causes the fluid or gas to evaporate.

• Temperature difference creates a density difference in the fluid or gas, causing warmer fluid or gas to rise and cooler fluid or gas to sink, resulting in convection.

• Temperature difference causes the fluid or gas to become stagnant.

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How does the density of a fluid affect convection?

• The density of a fluid affects convection by determining the temperature difference.

• The density of a fluid affects convection by determining the buoyancy force.

• The density of a fluid affects convection by determining the viscosity.

• The density of a fluid has no effect on convection.

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Give an example of natural convection.

• Cooling of a cup of hot coffee

• Melting of ice in a glass of water

• Burning of a candle

• Rising of hot air and sinking of cold air in a room

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How does heat transfer by convection occur?

• Heat is transferred through empty space.

• Heat is transferred through the vibration of particles in a solid.

• Heat is transferred by the movement of heated fluid from one place to another.

• Heat is transferred by the emission of infrared radiation.

Match each number from the diagram to the description of the event occurring at that position in the convection current.

• Cooling of the warmer material

• 4

• Movement of the denser material

• 2

• Movement of the less dense material

• 3

• Heating of the cooler material

• 1

Answer explanation

These are convection currents. Material (like magma in the mantle) is heated at the bottom of the current, becomes less dense and rises, cools at the top, becomes less dense, and sinks to the bottom, where it warms up and repeats the cycle.

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Which of the following best describes convection currents in the atmosphere?

• The movement of air due to differences in air pressure.

• The movement of air due to differences in temperature.

• The movement of air due to the Earth's rotation.

• The movement of air due to gravitational pull.

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Warm air rises and the cool air sinks demonstrates this type of heat transfer. 

• conduction

• convection

• radiation

• Insolation 

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Why does cold water sink in a convection current?

• Less dense

• more dense

• Less humid

• More humid

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Explain how convection is involved in weather patterns.

• Convection is only involved in weather patterns during the winter months.

• Convection is involved in weather patterns as warm air rises and cool air sinks, creating vertical movement of air masses.

• Convection only affects the temperature of the air, not the movement.

• Convection is not involved in weather patterns.

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