EX 9B Convection

Convection is the process of thermal energy transfer due to _____ changes.

• mass
• weight
• density
• length

Convection takes place only in ______, but not in ______.

• solids and liquids, gases
• solids and gases, liquids
• liquids and gases, solids
• gases, solids and liquids

The figure shows convection currents set up when water in each container is heated. Which part of the container needs to be heated so the water can set up such currents?

• A
• B
• C
• D

The figure shows convection currents set up when water in each container is heated. Which part of the container needs to be heated so the water can set up such currents?

• A
• B
• C
• D

The figure shows convection currents set up when water in each container is heated. Which part of the container needs to be heated so the water can set up such currents?

• A
• B
• C
• D

Convection currents flow because of the difference in densities of cold and hot liquids. When a liquid is heated, the mass _______ and the volume ______.

• increases, remains constant
• decreases, remains constant
• remains constant, increases
• remains constant, decreases

When a liquid is heated, the mass remains constant but volume increases. This cause its density to _______ and the liquid to _______.

• increase, rise
• increase, sink
• decrease, rise
• decrease, sink

Air-conditioners be placed near the ceiling because the _______ dense COOLED air from the top _____, setting up convection currents to cool the room.

• more, sinks
• more, rises
• less, sinks
• less, rises

The heating element of a kettle is always placed near the bottom of because the ______ dense HEATED water at the bottom ______, setting up convection currents to heat up the water.

• more, sinks
• more, rises
• less, sinks
• less, rises