1. K.R.E SOCIETY’S Karnatak Arts, Science and Commerce college Bidar
Dept of Electronics
By M S Chelva

2. Resistors Definition of Resistance Use the resistor color code
Understand what is meant by tolerance
Be able to add resistances in parallel
Be able to add resistors in series
Apply Ohm’s Law
Know what conditions are needed for Ohm’s Law

3. Definition of Resistance.
Resistance is a property of a conductive material that affects how much electrical current can flow through the material.
A conductor with a high resistance, is very good at limiting the flow of electrons through a circuit.
The units of resistance is the Ohm (Ω). More on that later

4. If you had me in IGCSE you will have seen this, here’s a recap...

5. Using the Resistor color Code
Resistors are way too small to print their values on the actual resistors. Take a handful (3 to 5) different resistors and you will see they will have 4 bands of colors on it.

6. Work out value of your resistors
Black
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Purple 7
gray 8
White 9
1st Band = Red = 2
2nd Band = Purple = 7
Multiplier = Green = 5 Zeros (00000)
Resistance = Ohms

7. Were your resistors exactly the correct resistance?NO
That’s what the tolerance is for. No one is going to make every single resistor the exact value (and can you imagine how fun the job of checking every single one would be?). So we give them a tolerance.
Gold = 5% tolerance
Silver = 10% tolerance

8. Adding resistors: Series
Simple as it looks, take 2 or more resistors and connect them in a chain. Add all their individual resistances together, and you’re done! Work out the total resistance of your 3-5 resistors, then measure the actual resistance!

9. Adding resistors: Parallel
This is a bit trickier. Combine your resistors in parallel and measure the resistance. Went down didn’t it? Write that down, now work out how we reduced the resistance...

10. Ohm’s Law
Resistance is proportional to voltage and current. As long as temperature stays the same.
V = IR
Rich hates the formula triangle!!! It is better if you can use algebra. But he understands if you are not as awesome at algebra as him.