For an electrical appliance to work, it must be ( ? ).

(a)  

The path for electricity to flow is called a(n) ( ? ).

(a)  

What is the 1st component of electric circuit?

(a)  

What is the 2nd component of electric circuit?

(a)  

What is the 3rd component of electric circuit?

(a)  

Name 3 circuit components on p.76.

(a)  

In Experiment 8.1, the bulb lights up only when the circuit includes ( ? ), which is an electric cell in this case.

(a)  

There must be ( ? ) from one end of the electric cell to the other.

(a)  

A circuit that includes a source of electrical energy as well as a complete path for electricity for flow from one end of the power supply to the other is called a(n) ( ? ).

(a)  

If there is a gap in the circuit, electricity cannot flow. This circuit is called a(n) ( ? ).

(a)  

When electricity flows through the circuit, the chemical energy stored in the electric cell is ( ? ).

(a)  

The light bulb changes ( ? ).

(a)  

Energy conversions take place at ( ? ).

(a)  

Explain Q2b on p.79 Checkpoint 8.1: There is a flow of electricity but ( ? ). This is a short circuit and the current will be dangerously large.

(a)  

Some materials allow electricity to flow through them. They are called ( ? ).

(a)  

Metals such as ( ? ) are good electrical conductors.

(a)  

Besides metals, some other materials like ( ? ) can also conduct electricity but not as well as metals can.

(a)  

Materials that do not allow electricity to flow through them are called ( ? ).

(a)  

( ? ) are examples of electrical insulators.

(a)  

Aluminium is used to make overhead power lines because ( ? ). Also, it is inexpensive.

(a)  

We can ( ? ) using a switch.

(a)  

A switch can be used to ( ? ) a circuit.

(a)  

An electrical appliance will be switched on and off when its switch is ( ? ) respectively.

(a)  

In science, we use symbols to ( ? ). These symbols are called circuit symbols.

(a)  

With circuit symbols and straight lines (representing connecting wires), we can ( ? ) to represent a circuit.

(a)  

Circuit diagrams can help us ( ? ) and communicate with one another clearly.

(a)  

What circuit symbol is this?

(a)  

What circuit symbol is this?

(a)  

What circuit symbol is this?

(a)  

What circuit symbol is this?

(a)  

What circuit symbols are these?

(a)  

The circuit must be drawn with ( ? )

(a)  

( ? ) is called electric current.

(a)  

Each atom has a nucleus surrounded by tiny ( ? ).

(a)  

The nucleus carries a positive charge while ( ? ).

(a)  

In metals, some of the electrons can ( ? ) and move freely within the metal.

(a)  

Electrons that can move freely are called ( ? ).

(a)  

When a metal is connected to an electric cell to form a closed circuit, the free electrons are ( ? ) towards the positive pole of the electric cell.

(a)  

The flow of free electrons forms a(n) ( ? ).

(a)  

Before the discovery of ( ? ), scientist believed that an electric current was a flow of positive charges from the positive pole of the of the electric cell to the negative pole.

(a)  

The current before the discovery of electrons is called the ( ? ).

(a)  

Refer to the analogy on the top of p.90. What are free electrons simulated as?

(a)  

Refer to the analogy on the top of p.90. What is the connecting wire simulated as?

(a)  

Refer to the analogy on the top of p.90. What is the electric cell simulated as?

(a)  

Refer to the analogy on the top of p.90. What is the light bulb simulated as?

(a)  

The size of an electric current is related to the number of free electrons that ( ? ).

(a)  

The more free electrons flowing through a current, the ( ? ) it becomes.

(a)  

We can use an ammeter to ( ? ).

(a)  

The unit of an electric current is ( ? ). (No need to write the abbreviation.)

(a)  

An ammeter has a red positive terminal and a(n) ( ? ).

(a)  

The ammeter should be connected so that the electric current ( ? ) and leaves from its negative terminal.

(a)  

When an electric current flows through a nichrome wire, some of the electrical energy ( ? ). As a result, the wire heats up.

(a)  

A nichrome wire heats up in electric current. The is called the ( ? ).

(a)  

The heating effect of an electric current is larger if the ( ? ).

(a)  

Some electrical appliances such as ( ? ) make use of the heating effect to work.

(a)  

In order to test the magnetic effect of electric current, we have to remove the ( ? ) from the two ends of a copper wire.

(a)  

What happens to the paper clips if you place a coil with electric current near them? They are ( ? ).

(a)  

When an electric current flows through a wire or a coil, the needle on a compass nearby ( ? ).

(a)  

Other than heating effect, an electric current also has a(n) ( ? ).

(a)  

When an electric current flows through a coil, the coil can attract iron paper clips like a magnet. This coil is called a(n) ( ? ).

(a)  

An electromagnet is useful because it acts like a magnet that ( ? ).

(a)  

Electromagnets are commonly used in devices such as ( ? ), electric bells, etc.

(a)  

Voltage is a measure of ( ? ) by a source of electricity such as electric cells.

(a)  

An electric cells with a higher voltage supplies ( ? ) to the free electrons in the circuit.

(a)  

Voltage is also related to the “( ? )” that makes free electrons flow in the circuit.

(a)  

We can use a voltmeter to ( ? ).

(a)  

The unit of voltage is ( ? ). (No need to write the abbreviation.)

(a)  

The voltmeter should b connected so that its positive terminal is connected ( ? ), and its negative terminal to the negative pole.

(a)  

When several electric cells are connected end-to-end in the same direction, the voltage across them is higher than ( ? ).

(a)  

The total voltage across the connected cells is ( ? ) of all the electric cells.

(a)  

It is hard to walk in a crowded MTR station as the people around you “resist” your motion. A similar concept about electric currents is called ( ? ).

(a)  

When the resistance of a circuit is higher, the electric current is ( ? ).

(a)  

A circuit of higher resistance has ( ? ) to the flow of electric current.

(a)  

A resistor is a circuit component with ( ? ).

(a)  

Resistors are used to control or limit ( ? ) in the circuits of electrical appliances.

(a)  

The ( ? ) the resistance of the resistor, the smaller the current.

(a)  

A rheostat is a circuit component ( ? ).

(a)  

There are two types of rheostats commonly used in a school laboratory: the sliding rheostat and the ( ? ).

(a)  

How many terminals does a sliding rheostat have?

(a)  

When we move or rotate the sliding contact of a rheostat, we change ( ? ) that the current flows through.

(a)  

One way to connect the two bulbs is ( ? ) to form a single-path circuit. This is called a series circuit.

(a)  

Two light bulbs the are connected in a circuit ( ? ) is called a parallel circuit.

(a)  

When one bulb is removed in a series circuit, the other ( ? ).

(a)  

When one bulb is removed in a parallel circuit, the other ( ? ).

(a)  

The currents ( ? ) at different points of a series circuit.

(a)  

In a circuit connected in series, the voltage across each light bulb and the voltage across the electric cells ( ? ).

(a)  

In a parallel circuit, the current in the main loop (denoted by $$I_m$$  ) ( ? ) when it flows into the branches.

(a)  

In a parallel circuit, part of the current flows through one branch (denoted by $$I_1$$  ) and the rest ( ? ) (denoted by $$I_2$$  ).

(a)  

The ( ? ) in the branches is equal to the current flowing in the main loop.

(a)  

The size of the current in each branch depends on ( ? ).

(a)  

The voltage in each branch of a parallel circuit ( ? ). It is also equal to the voltage across the electric cells.

(a)  

An electric kettle has a ( ? ), which is the nichrome wire.

(a)  

A filament light bulb makes use of a long thin ( ? ) to produce light.

(a)  

When a ( ? ) is placed near a magnet, a force is produced and this force can cause the conductor to move.

(a)  

( ? ) make use of the magnetic effect of electric current to produce kinetic energy and work.

(a)  

Electric motors are used at home in electrical appliances such as ( ? ).

(a)  

Electrical appliances are ( ? ).

(a)  

Energy converters convert electrical energy into ( ? ) for different purposes.

(a)  

Most electrical appliance in our homes ( ? ) the mains electricity.

(a)  

Mains electricity is generated in ( ? ).

(a)  

Main electricity is transmitted to our homes through ( ? ).

(a)  

The mains electricity in Hong Kong has a voltage of ( ? ).

(a)  

The voltage of the mains electricity in a place is called the ( ? ).

(a)  

To connect an electrical appliance to mains electricity, we need to ( ? ) into a mains socket.

(a)  

Name the 3 pins of a three-pin plug.

(a)  

Only the ( ? ) are responsible for delivering electricity to electrical appliances.

(a)  

Neutral wire ( ? ) for the current to complete the circuit.

(a)  

An electric cable is connected to the ( ? ) of our home, from which electricity is distributed to mains sockets.

(a)  

Light bulbs can ( ? ) when they are connected in parallel but not when connected in series.

(a)  

The circuit breaker is a safety device that ( ? ) related to the use of electricity.

(a)  

Each year, over ( ? ) fires are cause by electrical accidents in Hong Kong.

(a)  

The current in ( ? ) increases with the number of bulbs connected in parallel.

(a)  

If we connect too many electrical appliances to a(n) ( ? ), overloading may occur.

(a)  

A very large current resulted from very low resistance amongst the entire circuit is called a(n) ( ? ).

(a)  

When a fuse blows, the thin wire inside the fuse has ( ? )

(a)  

Each fuse has a fuse rating, which shows the ( ? ) that can flow through the fuse without blowing it.

(a)  

Once a fuse has blown, it cannot be used again, but need to be ( ? ).

(a)  

Circuit breakers are used in ( ? ) of our homes.

(a)  

An earth wire is a safety device that connects the metal casing of an electric appliance to the ground. This is called ( ? ).

(a)  

We might ( ? ) if there is not earth wire and the live wire touches the metal casing.

(a)  

We should use electrical appliances with ( ? ).

(a)  

We should ( ? ) around electrical appliances to prevent overheating.

(a)  

We should ask a ( ? ) to replace damaged wires and plugs, etc.

(a)  

We should not ( ? ) mains sockets.

(a)  

We should never touch switches or electrical appliances with ( ? ).

(a)  

We should not use electrical appliances in ( ? ).

(a)  

We should not use ( ? ) and universal adaptors, etc.

(a)  

We should never pull on a ( ? ) to remove a plug from a mains socket.

(a)  

We should not place ( ? ) near a heater or stove.

(a)  

Define power. Power is the amount of energy ( ? ).

(a)  

The unit of power is ( ? ). A larger power can be measured in ( ? ). (No need to write the abbreviation.) (Use a comma or a semicolon to separate your answers.)

(a)  

Other than a kilowatt-hour meter, we can also measure electrical energy using a ( ? )

(a)  

Kate forgets to turn off a 60 W desk lamp before going to bed. The desk lamp remains switched on for 9 hours. Calculate the cost of electricity wasted if the cost of electricity is $1.5 per unit.

(a)