Which of the three types of heat transfer (convection, conduction, and radiation) require no medium to transfer heat?

A. convection
Incorrect. Convection requires a medium to transfer heat through movement of a fluid (gas or liquid.)

B. conduction
Incorrect. Conduction requires a medium to transfer heat by contact of particles.

C. radiation
Correct! Radiation transfers heat through electromagnetic waves, and can transfer heat with or without a medium.

D. They all three require a medium to transfer heat.
Incorrect. Radiation is the one method that can transfer heat without a medium.

Source: Radiation, convection, conduction, Waifer X, Flickr

If I hold my hand above the candle and feel the heat, which types of heat transfer do I feel heating my hand?

A. Convection and radiation
Correct! My hand is warmed by rising warm air currents (convection) as well as electromagnetic radiation from the candle.

B. Conduction and radiation
Incorrect. Conduction requires contact of the particles that transfer heat.

C. Conduction and convection
Incorrect. The conduction requires contact of particles for heat transfer.

D. Conduction, convection, and radiation
Incorrect. Conduction occurs when particles make contact and transfer heat.

Source: Radiation, convection, conduction, Waifer X, Flickr

Look at the candle above. If I place my hands to either side of the candle, I feel heat. What type of heat transfer allows me to feel the heat?

A. conduction
Incorrect. My hands are not heated by direct contact with the candle.

B. convection
Incorrect. No rising fluid currents heat my hands, since they are out to the sides of the candle.

C. conduction and convection
Incorrect. Rising gases would not heat my hands (convection) and no particles make contact (conduction).

D. radiation
Correct! My hands are warmed by electromagnetic radiation emanating from the candle.

Source: Christmas Turkey, Christmas Stock Images

If the turkey is cooked in a traditional oven, which forms of heat transfer cook the turkey?

A. radiation and conduction
Incorrect. Radiation from the walls of the oven helps to cook the turkey, but there is little conduction.

B. convection and conduction
Incorrect. Conduction is not occurring to a large extent. Convection is the main type of heat transfer from heated air in the oven.

C. convection and radiation
Correct! The heat transfer occurs by convection of the warm air in the oven, and to a lesser extent by radiation from the walls of the oven.

D. radiation, convection and conduction
Incorrect. Radiation from the oven walls cooks the turkey, convection of the heated gases is the main heat transfer from moving currents of heated air, and very little conduction cooks the turkey.