Physics- electricity and circuits y9

Symbol for a fuse

A box with a straight line through it

The fuse protects the ____

appliance

Fuses have a high resistance so that

they heat up fast in case of a current overflow and melt

equation linking current power voltage

current= power/ voltage

How to work out the right fuse for an appliance

use the current, voltage, and power equation to find the working current of the appliance, then choose the next value of fuse above this number of Amps

What is an alternative to a fuse

A circuit breaker

Advantages of a circuit breaker

1. More sensitive

2. Work faster

3. More reliable

4. Can be reset rather than replaced

What are the names, colours and positions of the wires in a plug

• Neutral wire, blue, left

• Earth wire, yellow and green, middle

• Live wire, brown, right

Equation for Resistance, current and Voltage

Current= voltage/ resistance

The earth wire protects _____

The person

Explain how an earth wire works to protect against a faulty wire

1. If a faulty wire touches the metal casing, the appliance becomes live (charged).

2. The fault attracts an overflow of current which blows the fuse of the live wire.

3. The earth wire is connected to the casing, providing a path of lowest resistance.

4. The earth wire leads the electrical current to flow safely into the ground.

What safety measures to appliances with a metal casing use

Earthing

What safety measures to appliances with a plastic casing use

Double insulation

Symbol for double insulation

⧈

How does double insulation work

It stops the metal wires of a device from touching

Letter symbol for current

I

What type of current is Mains electricity

Alternating current, A.C.

What equation links Voltage, energy transferred, and charge

Energy= voltage x charge

Unit for charge

Coulombs (C)

Symbol for a variable resistor

box with an arrow through

Describe a standard circuit

Consists of an ammeter, a variable resistor, and a voltmeter around a different component. These are generally used to make voltage-current graphs.

The unit for power

Watts (W)