P2bL7  Components in Parallel

Key Words

Current  - flow of charge

Energy giver - source of energy

Energy takers - the components in the circuit.

Junctions - where two (or more) wires are connected.

Parallel - components each have their own branch of the circuit.

Potential Difference - voltage.

Power - rate of using energy

Splits - separates.

Grade E

This circuit has the same three lamps as before, but have a different arrangement.

We can see from the circuit diagram that each lamp has its own branch.  The three lamps are in parallel, so this is a parallel circuit.  There are junctions between each branch which are represented by the black dots.

If we set this circuit up and connect ammeters as shown, we find that:

A1 = A2 + A3 + A4

In other words, the currents add up.  An important rule for all parallel circuits is:

The currents in each branch add up to the total current.

Grade C

We can now measure the potential differences across each branch, as shown below:

We find that the voltage across each lamp is the same as the battery voltage.  This is true of any parallel circuit, regardless of whether the components are bulbs, resistors, or motors.

Grade A

From the Law of Conservation of Energy, the electrical energy supplied to the circuit must the the same as the energy supplied by the battery:

• The battery is the energy giver, or the source of energy

• The components are the energy takers; they cannot make their own energy.

The definition of potential difference is:

energy per unit charge (or joules per coulomb)