Science Chapter 9 (Electricity)

What does it mean when components are connected in series?

All components are connected end-to-end or one after the other.

How many paths does a series circuit have for current to flow?

Only one path

What happens to both the lamp and buzzer if the switch in a series circuit is opened?

They both stop operating

What is a parallel circuit?

A circuit with more than one path (branches) for current to flow.

What happens to the current at a branch in a parallel circuit?

The current is divided between the branches.

What does an ammeter do in a parallel circuit?

It shows the current shared between the branches.

What does an ammeter measure?

The current flowing in a component.

What is the unit for measuring current?

Ampere (A).

What is the rule for current in a parallel circuit?

The total current is equal to the sum of the current in all the branches.

What is one advantage of components in a parallel circuit?

They can be switched on and off independently.

What happens to other branches if a component in one branch stops working in a parallel circuit?

The other branches are not affected.

What is voltage measured in?

Volts (V).

What instrument is used to measure voltage?

A voltmeter.

Where is mains voltage supplied from?

The sockets found on walls of buildings.

What must the voltages of components in a series circuit add up to?

The voltage of the power supply.

What happens to the current when more components are added to a series circuit?

The current decreases.

Why does adding more components in a series circuit reduce the current?

It becomes more difficult for the power supply to push electrons around.

What effect does increasing the number of cells have in a series circuit?

It increases the current and the voltage across each component.

What is the voltage across each branch of a parallel circuit equal to?

The voltage of the power supply.

What happens when you add more cells to a parallel circuit?

The voltage across each branch increases, and the current through the cell and each branch increases.

What is resistance?

A measure of how easy or difficult it is for electrons to move through a material

What unit is resistance measured in?

Ohms (Ω).

What effect does resistance have on the flow of electrons?

It slows down the flow, lowering the current.

How does greater resistance affect the current in a circuit?

It makes the current smaller.

What type of materials have very low resistance?

Conductors.

What type of materials have very high resistance?

Insulators.

What are the wires in lamps called, and what is special about them?

Filaments; they have high resistance.

What is the formula for Ohm’s Law?

V = I × R (Voltage = Current × Resistance).

What is a resistor?

An electrical component designed to have a known resistance.

How is the resistance value shown on a resistor?

Using a colour code.

What is a variable resistor?

A component used to change resistance.