Home / iGCSE Physics (0625) 2.3.4 Consequences of energy transfer-Exam Style Questions

iGCSE Physics (0625) 2.3.4 Consequences of energy transfer-Exam Style Questions- New Syllabus

iGCSE Physics Exam Style Question Paper 2 - All Chapters

Question

A liquid passes through pipes inside a refrigerator. The liquid warms as the inside of the refrigerator cools. The warm liquid is then passed through pipes on the outside of the refrigerator to cool it before it goes back through the refrigerator.
The diagrams show two designs for the outside cooling pipes. One design has copper rods, called fins, attached to the pipes.
The outside pipes and fins can be painted silver or black.
Which design of outside pipes will cool the liquid most quickly?
A. painted black with fins
B. painted black without fins
C. painted silver with fins
D. painted silver without fins
▶️ Answer/Explanation
Correct Option: A

Detailed solution:

To cool the liquid quickly, the rate of thermal energy transfer to the surroundings must be maximized. Surface color significantly affects this; dull black surfaces are the best emitters of infrared radiation compared to shiny silver ones. Additionally, attaching copper fins increases the total surface area $A$ available for both radiation and convection. Since the rate of emission is directly proportional to the surface area, the design with fins provides a higher cooling rate. Therefore, the combination of a black surface for high emissivity and fins for increased area ensures the most rapid cooling.

Questions

Gas of volume 200 \(cm^3\) is trapped inside a container by a piston. The piston is pushed to the right and the volume of the gas decreases to 100 \(cm^3\). The temperature of the gas remains constant.

Which row states the effect that this has on the kinetic energy of the gas particles and the force per unit area exerted by the particles colliding with the inside walls of the container?

▶️Answer/Explanation

Ans C

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

...More iGCSE Physics Extended Questions
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