Danger from sparks

Making a spark
Look at the diagram. The belt on the electrostatic generator transfers charge to the dome. As the belt turns, the charge on the dome increases.
1. Copy and complete the sentences.
The greater the charge on the dome, the ____________ the potential difference between it and ____________.
When the potential difference is high enough, a _________ jumps through the air to a nearby ___________.
Sparks big and small
Static electricity can produce sparks. Often these sparks are very small. But sometimes they are huge.
2. Look at the pictures.
television screen,lightning and taking off a sweater
Then complete the following
Size of sparks (large or small)and How the static charge is produced in each case.

Preventing explosion at flour mills
Flour is made by grinding wheat to a very fine powder. The bits of flour make the air very dusty. This mixture of flour and air can be very dangerous. Just a tiny spark can make it explode.
3. Look at the diagrams.
There is a danger of a spark between the pipe and the container. Explain why.
4. How can such a spark be avoided?
Fire hazards with petrol tankers
Petrol is very flammable. A tiny spark can cause a serious fire when petrol or petrol vapor is open to the air.
At filling stations, petrol is transferred from tankers to underground tanks. There must be no sparks while this is being done.
5. In what two ways can petrol tankers produce static electricity?
6. Why does static electricity create a hazard when pumping petrol?
7. Write down two things that are done to prevent sparks.

Handle chips with care
Technicians who put electronic chips into circuits have special mats on their workbenches. These mats conduct electricity and are connected to earth. The technicians sometimes also wear wrist straps connected to earth.
8. Why are these precautions needed?
9. Explain how these precautions prevent damage to microchips.