Transcript OHM`s LAW PPT

Electrical Resistance
Electrons like any other moving body follow
the path of least resistance.
Which road would you
rather travel on?
Resistance
“Electrical Friction”
Opposition to the flow of moving
electrical charges
Symbol for Resistance
R
Unit of Measurement
ohm
“Resistance is Futile”?
If resistance is
“electrical friction”,
what benefits could
resistance provide
when making a circuit?
Is resistance futile in a lightbulb?
What kind of wires would increase
resistance in a circuit?
Resistance slows down moving
electrons.
When electrons slow down they
convert electrical energy into light,
heat and sound
What impacts resistance in a wire?
4 things that can change resistance
The resistance in a wire depends on:
A metals structural resistance to electron flow
The resistance in a wire depends on:
1. The type of metal in the wire
Which metals have
low resistance?
Which metals have
high resistance?
The resistance in a wire depends on:
1. The type of metal in the wire
Which metals have low
resistance?
Silver and Copper
Which metals have high
resistance?
Nichrome and Tungsten
The resistance in a wire depends on:
Length of the wire
The shorter the wire the less resistance there is
The resistance in a wire depends on:
Thickness (Cross Sectional Area) of the wire
The wider the wire the less resistance there is
The resistance in a wire depends on:
Temperature:
The colder it is the less resistance there is
Problem of the Day
Is resistance in a wire always bad?
bulbResistance.mp4
Problem of the Day
Why are different wires used with different
appliances?
http://www.stmary.ws/highschool/ph
ysics/home/notes/electricity/circuits/
ResistanceWire.htm
Scroll down on webpage to speaker scence
Ohm’s Law
V= I x R
Voltage (Volts)=
Current (Amps) times Resistance (ohms)
electric current is directly proportional to
voltage and inversely proportional to
resistance
Ohm’s Law Practice Problem
How much current is in a circuit with a 9 V battery
and a light bulb with a resistance of 3 ohms?
Current (A)
Voltage (V)
Resistance (Ω ) Formula
Looking for
this
I= ?
9V
3Ω
I = (V/R)
V divided by R
Answer with
Unit
Ohm’s Law Practice Problem
How much current is in a circuit with a 9 V battery
and a light bulb with a resistance of 3 ohms?
Current (A)
Voltage (V)
Resistance (Ω ) Formula
Answer with
Unit
Looking for
this
I= ?
9V
3Ω
3A
I = (V/R)
V divided by R
Ohm’s Law Practice Problem
What is the voltage of a circuit with 15 A of
current and a toaster with 8 ohms of resistance?
Current (A)
Voltage (V)
Resistance (Ω ) Formula
15 A
V= ?
8
V= I R
Answer with
Unit
Ohm’s Law Practice Problem
What is the voltage of a circuit with 15 A of
current and a toaster with 8 ohms of resistance?
Current (A)
Voltage (V)
Resistance (Ω ) Formula
Answer with
Unit
15 A
V= ?
8
15 A
V= I R