Define 'current'

The **flow **of **electric charge** around the circuit

When will current only flow across a component?

If there is a potential difference across that component

What is the unit for current?

Ampere: A

Define 'potential difference'

The **driving force** that pushes the current around

What is the unit for potential difference?

Volts: V

Define 'resistance'

Anything in the circuit which **slows **the **flow **(of the current) down

What is the unit for resistance?

Ohm: Ω

The **greater the resistance** across a component, the ____ the current that flows

(for a given ____ ____ across the component)

The greater the resistance across a component, the **smaller **the current that flows

(for a given **potential difference** across the component)

Which 2 factors does total charge through a curcuit depend on?

1. Current

2. Time

Current is the ____ of ____ of ____

Current is the **rate **of **flow **of **charge**

Write the formula triangle for current, total charge, and time

Current = charge / time

Current is measured in ____

Amperes (A)

Charge is measured in ____

Coulombs (C)

Time is measured in ____

Seconds (s)

**More charge** passes around the curcuit when a ____ current flows

More charge passes around the curcuit when a **bigger **current flows

Example:

A battery charger passes a current of 2.5 A through a cell over a period of 4 hours. How much charge does the charger transfer to the cell altogether?

Q = I x t = 2.5 x (4 x 60 x 60) = 36 000 C (36 kC)

Potential difference is the ____ ____ per ____ ____ ____

Potential difference is the** work done** per **unit of charge**

Give the formula for potential difference, work done, and coulombs

**P.D.** (V) = **work done** (W) / **charge **(Q)

Potential difference across an electrical component is...

... The **amount of energy **transferred by that electrical component (e.g. to light and heat energy by a bulb) **per unit of charge**