Thermal Energy Questions

Question 1

How is energy transferred from the hot plate to heat up the potato?

Answer 1

• There is conduction from the hot plate to the pan.
• There is conduction through the pan.
• There is conduction from the pan to the water.
• There is convection in the water.
• There is conduction from the water to the potato.
• There is conduction through the potato.

Question 2

How does the microwave transfer energy to the potato?

Answer 2

The electromagnetic waves (from the microwave) penetrate into the food. This causes the water molecules to vibrate more and there is conduction through the rest of the potato.

Question 3

This is an induction cooker:

• The potato is placed in water in a metal pan.
• An alternating current is switched on in the coil under the pan.
• The coil does not heat the cooker’s surface.

How is energy transferred to heat up all of the potato?

Answer 3

• In this cooker, there is electromagnetic induction.
• The coild creates a magnetic field around it.
• The magnetic field cuts through the metal pan.
• The field changes (because it’s an alternating current).
• A voltage is induced in the pan.
• The induced voltage causes a current in the pan.
• The current makes the pan get hot.
• The water is then heated up by conduction and the water convects energy to the potato.