1. Agenda Bell Work
• Van der Graaf 1. What parts are in a
simple circuit? How is
• Notes: Ohm’s Law it set up?
• Practice WS
2. What is voltage?
3. What is ampere?
• Static vs. Current Electricity
Quiz tomorrow 4. How do these two
relate to each other in
a circuit?
4. Objectives
1. Describe the parts of Ohm’s Law
- Volts, amps, and resistance
1. Given two known values, calculate
the unknown using Ohm’s Law
5. Ohm’s Law
Relationship between current,
resistance, and voltage
6. Electrical Resistance
Resistance of
electrons to flow
in a circuit
What affects
resistance?
• Length, and width
and type of wire
7. Shown by a zig-zag
symbol in a circuit
Controls current
Measured in ohms
8. Ohm’s Law
Current is proportional to the voltage
and inverse to the resistance
Current(I) = Voltage/Resistance
Units:
• Amperes = volts/ohms
9. 1 volt across a circuit with a resistance of
1 ohm produces a current of 1 ampere
What is the current if there are 12 volts
across the same circuit?
What about If the resistance increased to
two ohms with 1 volt?
10. How much current flows through a
lamp with a resistance of 60 ohms
when the voltage across the lamp is
12V?
What is the resistance of an electric
frying pan that draws a current of
12A when connected to a 120-V
circuit?
11. Electric Shock and Ohm’s
Result from the current through the
body
Depends on voltage and body’s
electrical resistance (100 ohms to
500,000 ohms)
12. Effect of Electric Current on the
Body
Current(A) Effect
0.001 Can be felt`
0.005 Is painful
0.010 Causes involuntary muscle
contractions (spasms)
0.015 Causes loss of muscle control
0.070 Goes through the heart, serious
damage, probably fatal if lasts
longer than 1s
13. At 100,000 ohms how much current
will flow through your body if you
touch the terminals of a 12-V
battery?
If your skin is very moist, so that
your resistance is only 1000 ohms,
and you touch the terminals of a 12-
V battery, how much current do you
receive?
14. To receive a shock there must be a
difference in voltage ( a circuit must
be formed)
Electron flow will follow the path of
least resistance
15. Plugs and sockets
Wired with three connections
Two flat prongs are for current-
carrying
The larger round prong connects to a
wire in the ground (grounded)
