Domestic Uses And Safety Flashcards

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1
Q

How is current supplied by cells and batteries and what does it mean

A

Directly, (direct current) always flows in the same direction

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2
Q

How does time affect p.d and current change in a bulb when direct current?

A

No change, always the same

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3
Q

How is current supplied by main socket and what does it mean

A

Alternating, constantly change direction (in the circuit)

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4
Q

What is frequency and voltage in the UK

A

Frequency=50hz
Voltage=230V

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5
Q

How does voltage affect currents flow in a alternating current, and how many times does this change occur per second?

A

When voltage is positive current flows in one direction and when negative it flows in the opposite direction. 50 times per second

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6
Q

What do each wires do?

A

Live=provides alternating voltage from power supply
Neutral=completes circuit
Earth=carries current if there is a fault

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7
Q

How does a earth wire work?

A

When there is a fault in circuit, current will flow in it

The earth wire has a lower resistance than a human body

More current will flow in the wire than in the human

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8
Q

What is the fuse connected to?

A

Live wire

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9
Q

How do fuses work?

A

Large current flows through fuse

Maximum rating of fuse is exceeded

Fuse blows

Fuses reduce risk of electrical fires only and not electrocution

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10
Q

How do circuit breakes work (magnetically activated)?

A

Use an electromagnet to detect overcurrent

When current exceeds the safe limit, the coil generates a strong magnetic field

This attracts a metal armature

This triggers the circuit breaker to open, isolating the fault

Quick response minimises damage and fire risks

After fixing the fault, manual reset is possible

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11
Q

What appliances do not need an earth wire?

A

Double insulated

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12
Q

Why do double insulated appliances not need an earth wire?

A

Designed with two layers of insulation and do not have exposed metal parts

They are classified as class 2 appliances

No earth wire is needed

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