Science - Chapter 8.7-8.8

Some electrical appliances like electric kettles, work on the heating effect of electric current. They have ________________ ______________, which are usually nichrome wires.

heating elements

What is inside of a filament lightbulb?

tungsten filament

What happens when a current flows through the filament in a filament lightbulb?

The filament becomes so hot that it glows and produces light

Electrical energy is converted into thermal energy for use in the __________ _____________ in electrical appliances.

Heating effect

The moving parts of electrical appliances are driven by _________ ___________, which make use of the magnet effect of electric current to work.

electric motors

Electric motors can convert electrical energy into ____________ energy.

kinetic

Examples of electrical appliances in our homes that work on the heating effect of electric current.

electric kettles, electric stove, hairdryer

Examples of electrical appliances in our homes that work on the magnetic effect of electric current.

electric fans, vacuum cleaners, washing machines

The ________ of a washing machine is driven by an electric motor.

drum

Electrical appliances are _____________ _______________ useful for different purposes

energy converters

An electric motor works on the _________ effect of electric current

magnetic

Most electrical appliances in our homes get power from the ____________ ___________

Mains electricity

What’s the voltage of the mains electricity in Hong Kong?

220 V

What is the voltage of 220 V called?

mains voltage

To connect an electrical appliance to mains electricity, where do we need to insert its plug into?

mains socket

What’s the name of the green-yellow wire?

earth wire

What’s the name of the brown wire?

live wire

What’s the name of the blue wire?

neutral wire

What’s hole A?

Earth hole

What’s hole B?

live hole

What’s hole C?

Neutral hole

The live and neutral wires are responsible for ________________________________________.

Delivering electricity to electrical appliances

Which two wires are responsible for delivering electricity to electrical appliances?

live and neutral wires

Which wire carries the voltage that drives the current flowing through the appliance?

live wire

Which wire provides a return path for the current to complete the circuit?

Neutral wire

Mains electricity is transmitted from power plants to our home through a ________ ___________.

Electric cable

Domestic circuits are __________ circuits so that the electrical appliances can operate independently.

parallel

What device protects us from accidents related to the use of electricity?

circuit breaker

Connecting too many electrical appliances to a mains socket causes __________________ and the current will be too large.

overloading

When can short circuits occur?

When wires are loose or worn out

What will happen if a short circuit occurs?

It leads to a very large current so the circuit becomes very hot and may catch fire

If a wire is connected in parallel across a heating element, a __________ ____________ is formed. The current may become very large and the circuit overheats.

short circuit

Name two examples of places where fuses can be found.

electric plugs, universal adaptors

What will happen if a current of 6A passes through a fuse with the rating of 5A.

It will blow and break the circuit

Where can circuit breakers be found?

consumer units

What’s the main difference between circuit breakers and fuses?

circuit breakers don’t have to be replaced after breaking a circuit

What will happen if the current exceeds the rating in a circuit with a circuit breaker?

the circuit breaker will switch off by itself to break the circuit

The _________ wire is connected to the metal casing of an appliance. It protects us from getting an electric shock.

Earth

What will happen if we touch a faulty appliance with no earth wire?

We will get an electric shock