HEAT TRANSFER
What are the three main methods of heat transfer?
Conduction, convection, and radiation.
What usually happens to particles when a substance is heated?
Their movement increases.
What is an insulator?
A material that limits or slows the transfer of energy.
What is a conductor?
A material that allows energy to transfer easily.
What provides energy to a simple battery-powered circuit?
A battery.
Heat energy moves from an object with a higher temperature to an object with what?
A lower temperature.
What is expansion?
An increase in the size or volume of a substance.
Which is generally a better thermal insulator: a metal spoon or a wooden spoon?
A wooden spoon.
Name one metal that conducts thermal energy well.
Copper, aluminum, or steel.
What must a circuit have for electrical current to flow continuously?
A complete, closed loop.
A metal spoon becomes warm after sitting in hot soup. What type of heat transfer occurs through the spoon?
Conduction.
What is contraction?
A decrease in the size or volume of a substance
Why is foam often used in a cooler?
It slows thermal energy transfer and helps keep contents cold.
Why are rubber or plastic often used to cover electrical wires?
They are electrical insulators that help prevent unwanted electrical current from reaching people or other objects.
What is an open circuit? (Do you have power?)
A circuit with a break in its path that prevents continuous current flow.
Warm air rises while cooler air sinks in a room. What type of heat transfer does this demonstrate?
Convection
A metal object is heated and becomes larger. What caused this change?
The transfer of thermal energy increased particle motion and changed the spacing between particles.
Two cups contain equally hot water. One is insulated and one is not. Which should cool more slowly?
The insulated cup.
A student tests a material and finds that it allows electrical current to pass through a circuit. How should the student classify it?
As an electrical conductor.
In a series circuit, what happens if one bulb is removed and the circuit path breaks?
The circuit opens and the bulbs in that path go out.
You feel warmth from the Sun even though space between Earth and the Sun is mostly empty. How does the energy travel?
Radiation, through electromagnetic waves that do not require matter.
Why might engineers leave small gaps between sections of a bridge?
To allow the materials to expand when heated and reduce the risk of damage.
A student tests two insulated containers. What should the student measure over time to compare their effectiveness?
The water temperature over time, keeping the starting conditions as similar as possible.
A material transfers heat easily but does not allow electrical current to pass through it easily. Can it be a thermal conductor and an electrical insulator at the same time?
Yes. Thermal and electrical conductivity are different properties.
A student builds a flashlight with a battery, wires, a bulb, and a switch. The bulb does not light. Name two possible problems.
The switch is open, a wire is disconnected, the battery is dead or incorrectly connected, or the bulb is not making proper contact.