EFFECT OF HEAT

If boiling water is poured into thick glass, it often cracks. This is because... 

• of the unequal expansion and contraction of the inner and out glass layer.
• the outer glass layer expands more than the inner glass layer when in contact with water.
• the glass is very fragile. 
• the difference in temperature between the inside and outside of glass in very big.

Bimetallic strips are commonly found in all of the following except...

• electric iron.
• rice cooker.
• refrigerator.
• clinic thermometer.

A bimetallic strip is made up of _____________________ welded together.

• two metals of the same kind 
• two different metals that expand and contract unequally
• two different metals that expand and contract equally

Which metal, A or B, expands the most upon heating? And what metal is it?

• A; Iron
• A; Brass
• B; Iron
• B; Brass

The picture shows a bimetallic strip in a fire alarm. When there is a fire outbreak, the bimetallic strip will get hot, ....

• bend downwards, complete the circuit and the alarm rings.
• bend upwards, open the circuit and the alarm will not ring.
• becomes longer, open the circuit and the alarm will not ring.

What is a thermostat?

• It keeps temperature high all the time.
• It keeps temperature low all the time.
• It keeps the temperature constant all the time.

What is the temperature at which a solid changes into a liquid called?

• boiling point

• melting point

• freezing point

• absolute zero

True or False? Substances expand as they are cooled.

• True

• False

What happens to the thermal energy of a substance as it freezes?

• the substance gains thermal energy

• the substance loses thermal energy

• the substance absorbs thermal energy

• there would be no thermal energy

The bimetallic strip in a thermostat bends as it is heated because the two metals in the strip ______ at different rates

• expand

• retract

• freeze

• boil