Microwaves
3 marks · NormalA person spends a long time standing close to a malfunctioning microwave oven that is leaking microwaves.
State and explain one harmful effect this exposure could have on the person’s body.
Suggest one way the design of a microwave oven helps to prevent this effect.
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(a) Microwaves can cause heating of body tissues, which can burn or damage cells if exposed excessively.
(b) The metal screen or mesh on the oven door reflects microwaves and keeps them inside.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Identifies potential harm (heating/burning tissue or cells).
A1 (a) · 1 mark · Explains mechanism: microwaves are absorbed by water molecules in body, causing heat.
B1 (b) · 1 mark · Correctly states mesh/screen reflects microwaves or keeps them contained.
Worked solution
a) Microwaves are absorbed by water in the body and can heat or burn tissues, causing pain or even cell damage if exposure is excessive.
b) A metal mesh or screen in the oven door reflects microwaves back into the oven, preventing them from escaping.