Download parallel circuits

What we will do today:
•
Carry out experiments to investigate the
following relationships:
1. Current in a parallel circuit
2. Voltage in a parallel circuit
Current in a parallel circuit
(don’t copy)
• What is a parallel circuit?
• What apparatus would be required to
measure the current at different
points in a parallel circuit?
Current in a Parallel Circuit
Point on circuit
Value of Current (A)
Is (supply current)
I1
I2
• In a parallel circuit, the sum of the
current across the components equals
the supply
• Is = I 1 + I 2 …
Voltage in a parallel circuit
• What apparatus would be required to
measure the voltage at different
points in a parallel circuit?
Voltage in a Parallel Circuit
Point on circuit
Value of Voltage (V)
Vs (supply voltage)
V1
V2
• In a parallel circuit, the voltage
across all components is the same as
the supply.
• Vs = V1 = V2 …
What have we learned today?
• In a parallel circuit, the sum of all the
currents across the components is
the same as the supply.
• Is = I 1 + I 2…
• In a parallel circuit, the sum of all the
voltages is the same as the supply.
• V s = V1 = V2 …
Example 1 – find the missing
values below
•
•
•
•
Is = I1 + I2
0.6 = 0.2 + I2
I2 = 0.6-0.2
I2 = 0.4A
•
•
•
•
Vs = V1 = V2
6V = 6V = 6V
V1 = 6V
V2 = 6V
Example 2 – find the missing
values below
• Is = I1 + I2 + I3
• Is = 0.2 + 0.6 + 0.4
• Is = 1.2 A
• Vs = V1 = V2 = V3
• V2 = 4V
• So, Vs = 4V
2007
2010
2008
2007
2010 Qu: 22
2007
2009
2010
2007 Qu: 22
2004, Qu: 10
2006, Qu: 9