Revision and summary.

1. Revision
notes
Ohm’s
Law:
V
I R
Resistors
in
series
Resistors
in
parallel
R1=10ohm
R1=10ohm R3=30ohm
Same
voltage
across
the
resistors
R2=20ohm
R2=20ohm but
different
currents
through
I individual
resistors.
R3=30ohm
Vs=10V
Same
current
through
all
the
resistors
but
I
different
voltages
across
individual
resistors.
Vs=10V
Total
resistance
RT
Total
resistance
RT
RT = R1 + R2 + R3 = 10 + 20 + 30 = 60Ω
1 1 1 1 1 1 1
= + + = + + = 0.1+ 0.05 + 0.0333 = 0.1833
RT RT R1 R2 R3 10 20 30
1
⇒ RT = = 5.46Ω
0.1833
RT
I
Vs=10V
I
Vs=10V
Total
Voltage
Total
and
individual
Voltages
No
need
to
calculate.
Total
voltage
=
10V
No
need
to
calculate.
Voltage
across
each
resistor
=
10V
Total
and
individual
Currents
Total
current
V 10 V 10
I= S = = 0.167A
I= S = = 1.83A
RT 60 RT 5.46
Individual
voltages
Individual
currents
I1 R1=10ohm
R1=10ohm R3=30ohm
R2=20ohm
V3 I2 R2=20ohm
V1
V2
I
I3 R3=30ohm
Vs=10V
I
V1 = IR1 = 0.167x10 = 1.67V
V2 = IR2 = 0.167x20 = 3.33V
Vs=10V
V3 = IR3 = 0.167x30 = 5V