Problems with static electricity
3 marks · NormalDescribe two dangers of static electricity in everyday life and how each can be reduced or prevented.
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1. Aircraft can build up static charge during flight; earthing the aircraft after landing prevents sparks during refuelling. 2. Static charge builds up when leaving a car on a dry day; touching a metal part of the car before refuelling allows the charge to escape safely.
Must show: two distinct dangers, one method of prevention each
Also accept: 1. Clothing charged by friction could cause a shock; using cotton fabrics reduces charge build-up. 2. Static charge in fuel pipes; earthing the pipes before transferring fuel.
Common mistakes: Listing only one example; Describing a danger but not the prevention.
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Marking points
B1 · 1 mark · Describes a correct danger of static electricity.
B2 · 1 mark · Describes a second correct danger.
B3 · 1 mark · Provides valid prevention method for at least one danger.
Worked solution
1. Aircraft become charged by friction as they fly. If not earthed before refuelling, a spark could ignite the fuel. To prevent this, the aircraft is connected to earth with a conductor after landing. 2. Getting out of a car on a dry day, you can get a shock as static charge escapes. To prevent this, touch a metal part of the car while getting out to allow slow discharge of the static electricity.