Question
Which change will cause a decrease in the rate of radiation emitted by an object?
A changing the surface colour from white to black
B changing the surface texture from dull to shiny
C increasing the surface temperature
D increasing the surface area
Answer/Explanation
Ans: B
Question
Some hot water is sealed inside a metal can. The can is in a vacuum in outer space. The hot
water slowly cools down.
How does the thermal energy escape into space?
by conduction then convection
by conduction then radiation
by evaporation then convection
by evaporation then radiation
Answer/Explanation
Ans: B
Question
Four objects, made of the same material and having the same mass, are at the same
temperature. The objects have different surfaces and different surface areas.
Which object emits infra-red radiation at the greatest rate?
| surface | surface area |
A | dull | large |
B | dull | small |
C | shiny | large |
D | shiny | small |
Answer/Explanation
Ans: A
Question
The diagram shows the cross-section of a vacuum flask containing a hot liquid in a cold room.
X and Y are points on the inside surfaces of the walls of the flask.
How is thermal energy transferred between X and Y?
A by conduction and convection
B by conduction only
C by radiation and convection
D by radiation only
Answer/Explanation
Ans: D
Question
Which statement about the transfer of thermal energy is correct?
A. All metals conduct thermal energy equally well.
B. Convection can only occur in solids or liquids.
C. Convection occurs in liquids because hot liquid is more dense than cold liquid.
D. The radiation that transfers thermal energy is a type of electromagnetic radiation.
Answer/Explanation
Ans: D