Page 159 - Science Coursebook

10.9 Components in parallel

Current in parallel circuits
The circuit diagram shows the same circuit as

before, but drawn slightly differently to make

it easier to understand how the current flows
when two identical components are connected B
in parallel.
The current flows from the positive end of the

cell. When it reaches point A, it divides. Half −

of the current flows through one lamp, and half +

flows through the other. When the two currents
reach point B, they join together again. Then
they flow back to the cell.

A
This means that, when there are two identical
lamps in parallel, there is twice as much current The blue arrows show how the
as when there is only one lamp. Each lamp gets current flows in this parallel circuit.
its own share of the current.

This shows that it is easier for the current to

flow when two components are connected in
parallel in a circuit. There is less resistance, and
so the current is bigger.

Question
1 a Draw a circuit diagram to show a circuit with one cell and two resistors
connected in parallel. Include an ammeter to measure the current flowing

from the cells.

b Add arrows to show how the electric current flows round the circuit.
c Mark with an X the point where the current divides.

d If each resistor has a current of 0.5 A flowing through it, what current
would the ammeter show?

Summary
• Components connected side by side are in parallel.
• The current in a circuit divides as it passes through the components
connected in parallel.

10 Electricity 157