# P4 Flashcards

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• Created by: 12karora
• Created on: 29-06-16 12:33
What is a static charge?
A charge that does not move as it is created by rubbing two electrical insulators together
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How are electric shocks caused?
When negative electrons build up in you due to static electricity. When you earth yourslef the charge escapes and shocks you.
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How do postives and negatives work?
Positives never move but negatives do. Negative elctrons are attracted to the postive so move between objects.
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How does a dust precipitator work?
The wires in a grid are charged negatively. As dust particles go past they become negatively charged. The charge on the wires cuases the plates to become positive. The plates attract the dust and then it is removed.
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How does paint spraying work?
The nozzle is postively charged whilst the object to be painted is negative. The opposite charges cause the powder to attract to the object. As it moves through the paint gun it becomes negative. Like forces repel so the powder spreads for even coat.
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What is the calculation for resistance?
Resistance= Voltage/Current
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Explain resistance
How easily current flows. As voltage increases, bulb gets brighter. This makes it hotter and atoms vibrate more. Resistance increases as it directly links to temperature.
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What are the wires in a plug?
The earth wire gives a low resistance path to the ground to discharge an appliance. The live wire carries electric current to mains appliances. The neutral wire is kept at 0V and is a return path for mains electricity.
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What is ultrasound?
A longitudinal wave above 20,000 Hz
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What are uses of ultrasound?
It can check for development of foetus' and to look for tumours. High powered beams can break down kidney stones. It can break opaque lens from patients suffering from a cataract. It can measurethe speed of blood.
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## Other cards in this set

### Card 2

#### Front

How are electric shocks caused?

#### Back

When negative electrons build up in you due to static electricity. When you earth yourslef the charge escapes and shocks you.

### Card 3

#### Front

How do postives and negatives work?

### Card 4

#### Front

How does a dust precipitator work?

### Card 5

#### Front

How does paint spraying work?