Infrared
3 marks · NormalA metal plate is heated by an infrared lamp. The initial temperature of the plate is , and it rises to after 3 minutes of heating.
Describe, using ideas about infrared radiation, why the temperature of the plate increases when placed under the lamp.
State an effect of increasing the power of the lamp on the rate at which the plate heats up.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) — · must show Plate absorbs infrared, Energy increases kinetic energy of particles/temperature rises
(b) The plate would heat up faster. · must show Faster heating/higher temperature rise per second
Common mistakes: Saying plate reflects infrared
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States the plate absorbs infrared radiation from the lamp.
B2 (a) · 1 mark · Energy absorption increases the temperature of the plate.
B3 (b) · 1 mark · States that increasing power increases the rate of heating/plate heats faster.
Worked solution
a) The plate absorbs infrared radiation from the lamp. This energy increases the vibration of particles in the plate, causing its temperature to rise.
b) If the power of the lamp increases, the plate will heat up faster (the temperature rise per second increases).