1. Ohm’s Law and Circuit Basics
Venus Is Round
Ohm’s Law and Circuit Basics

2. Current in Circuits Ohm’s Law CURRENT is a REACTION to
the ACTION of VOLTAGE
How much current depends on:
VOLTAGE  MORE voltage = MORE current
RESISTANCE  MORE resistance = LESS current
Ohm’s Law

3. Example #1
The voltage supplied to a circuit with a resistance of 100 ohms is 25 volts. How much current will flow in this circuit?
I = V / R
I = 25 V / 100 Ω
I = 0.25 A

4. Example #2
A current of 2.0 amperes flows through a circuit with a resistance of 10 ohms. What is the voltage supplied to the circuit?
I = V / R
2A = V / 10Ω
V = 20V

5. Example #3
A 10 volt battery is connected to a circuit, allowing 5 amperes of current flow. Calculate the resistance of the circuit.
I = V / R
5A = 10V / R
R = 2Ω

6. Circuit A path through which current flows
from an area of high voltage to an area of
low voltage.

7. Circuit Elements Other Elements Resistances Measurement Devices
Voltage sources
Fixed resistor – resistance
does NOT change once installed
Opens and closes the circuit turning
current flow on or off
Resistance CAN be changed after installation
Voltmeter is a device
for measuring
VOLTAGE
How hard are electrons
being pushed?
Ammeter is a device
for measuring CURRENT
How many electrons
flow per second?
Provide electrical potential for electrons – “PUSHING”
or “PUMPING” them through the circuit
Special resistor – used to produce light!

8. Measurements V V V A A V 100V R = 10Ω 10A 10A 0V 0V Voltmeter measures
RELATIVE
differences
from OUTSIDE
the circuit
Ammeter measures
flow INSIDE
the circuit
V = 100V V
100V