Transcript More about resistance

5.2
More about resistance
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR,
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
5.2
More about resistance
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR,
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
5.2
More about resistance
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR,
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
5.2
More about resistance
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
Resistors in series:
I
I
I
R1
R2
R3
RT
V1
V2
V3
VT
Resistors in series can be replaced by one single resistor:
VT
I
=
V1
+
V2
+
V3
But V = IR
I RT
=
I R1
+
I R2
+
I R3
I RT
=
I R1
+
I R2
+
I R3
RT
=
R1
+
R2
+
R3
5.2
More about resistance
I1
IT
Resistors in parallel:
I
R1
I2
RT
R2
I3
V
R3
V
Resistors in series can be replaced by one single resistor:
IT
=
I1
V
RT
=
V
R1
V
RT
=
V
R1
=
1
1
RT
+
+
I2
+
I3
V
R2
+
V
R3
But V = IR and I =
R1
+
+
V
R2
1
R2
+
+
V
R3
1
R3
V
R
5.2
More about resistance
I1
IT
Resistors in parallel:
I
R1
I2
RT
R2
I3
V
R3
V
Resistors in series can be replaced by one single resistor:
IT
=
I1
V
RT
=
V
R1
V
RT
=
V
R1
=
1
1
RT
+
+
I2
+
I3
V
R2
+
V
R3
But V = IR and I =
R1
+
+
V
R2
1
R2
+
+
V
R3
1
R3
V
R
5.2
More about resistance
I1
IT
Resistors in parallel:
I
R1
I2
RT
R2
I3
V
R3
V
Resistors in series can be replaced by one single resistor:
IT
=
I1
V
RT
=
V
R1
V
RT
=
V
R1
=
1
1
RT
R1
+
I2
+
I3
+
V
R2
+
V
R3
+
V
R2
+
V
R3
+
1
R2
+
But V = IR and I =
1
R3
V
R
5.2
More about resistance
I1
IT
Resistors in parallel:
I
R1
I2
RT
R2
I3
V
R3
V
Resistors in series can be replaced by one single resistor:
IT
=
I1
V
RT
=
V
R1
V
RT
=
V
R1
=
1
1
RT
R1
+
I2
+
I3
+
V
R2
+
V
R3
+
V
R2
+
V
R3
+
1
R2
+
But V = IR and I =
1
R3
V
R
Resistors in parallel:
I1
IT
I
R1
I2
RT
R2
I3
V
R3
V
Resistors in series can be replaced by one single resistor:
IT
=
I1
V
RT
=
V
R1
V
RT
=
V
R1
=
1
1
RT
R1
+
I2
+
I3
+
V
R2
+
V
R3
+
V
R2
+
V
R3
+
1
R2
+
But V = IR and I =
1
R3
V
R
5.2
More about resistance
Resistance heating
5.2
More about resistance
Resistance heating
Charge carriers transfer kinetic energy to positive ions through repeated collisions.
The pd across the material then provides an accelerating force to the charge carrier
which then collides with another positive ion.
P = I V
V = I R
Resistance heating
Charge carriers transfer kinetic energy to positive ions through repeated collisions.
The pd across the material then provides an accelerating force to the charge carrier
which then collides with another positive ion.
P = I V
Energy per second transferred
to the component P:
P = I2 R
V = I R
5.2
More about resistance
Resistance heating
Charge carriers transfer kinetic energy to positive ions through repeated collisions.
The pd across the material then provides an accelerating force to the charge carrier
which then collides with another positive ion.
P = I V
Energy per second transferred
to the component P:
In the steady state this equals
the heat transfer to the surroundings
P =
I2
R
V = I R
P = V2
R