Download Resistance

Resistance
• Resistance is the property of a substance that
measures its ability to impede the flow of
electrons in conductors.
• As electrical current flows through a
resistor,electric potential (voltage) is lost. (I.e.
the electrons have more potential energy
before passing through the resistor)
• Symbol: R
• Unit: ohm (Ω)
• Measuring Device: Ohmmeter
What does a resistor do when it is in a
circuit?
• Reduces the current in a circuit
• Ohm’s Law – the potential difference
between 2 points on a conductor is
proportional to the electric current
flowing through the conductor
• Ohm’s Law: V = I x R
V
I
R
Name
Symbol in
Formula
I
Symbol for Unit
Voltage/Potential
Difference
Energy
V
V
E
J
Charge
Q
C
Resistance
R
Ω
Current
A
Ohm’s Law:
The potential difference between two
points on a conductor is proportional
(directly related) to the electric current
flowing through the conductor.
Sample Calculations
1. A load has 1.2 A of current flowing through
it. The voltage across the load is 6.0 V.
Calculate the resistance of the load.
Given: I = 1.2A
V = 6.0V
Required: R = V÷I
Analysis: R = 6.0÷1.2
Solution: R = 5.0 Ω (this is option z on your computer)
2. Calculate the Resistance given the following
data:
a)
V = 120 V
I = 1.1 A
b) V = 1.5 V
I = 0.015 A