Problems with static electricity

2 marks · Normal

Some factories use metal pipes to transport flammable powders. Explain why these pipes must be earthed.

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So that any static charge built up as powders move does not cause a spark that could ignite the flammable material.

Also accept: Earthing allows static charge to escape safely, preventing sparking and fire.

Common mistakes: Saying 'for safety' without reference to static or the risk of ignition.

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Marking points

B1 · 1 mark · States static charge can build up as powders move.

B2 · 1 mark · Explains earthing prevents sparks/fire.

Worked solution

Friction from flammable powders moving through pipes can create static electricity. Earthing allows this charge to flow away safely, stopping sparks that could ignite the powders.