Ohm’s law
* Electrical resistance is the property of a substance that slows down the movement of electrons and converts electrical energy into other forms of energy,
* The unit used for measuring resistance is the ohm. An ohmmeter can be used to measure resistance.
* A resistor is a component in a circuit that has a specific resistance. resistors are used to control current or voltage to suit the needs of other electronic devices in the cursuit.
* Ohmic resistors are a load that does not change its resistance with temperature. An ohmic resistor obeys ohm's law graph will be a straight line.
* Non-ohmic resistors do-not obey ohm's law. Example light bulbs because as the temperature of the bulb increases the value of the resistance changes. It has a variable resistance value.
* Ohm’s law is a mathematical equation that shows how voltage, current, and resistance are related:
resistance=voltage/or R=V/I
where the R stands for resistance, V stands for voltage, I stands for current
* The values of the resistor can be determined by calculation or by plotting a graph of the experimental data for the resistor, and then measuring the slope of the V/I graph.
Example:
1. What is the voltage drop accessing a bulb that has a resistance of 144 ohms and a current of 0.50 A is flowing through it.
Where:
* VVV is the voltage (in volts),
* III is the current (in amperes),
* RRR is the resistance (in ohms).
Given:
* R=144 ΩR = 144\ \OmegaR=144 Ω
* I=0.50 AI = 0.50\ \text{A}I=0.50 A
Now calculate:
V=0.50 A×144 Ω=72 VV = 0.50
Answer: The voltage drop across the bulb is 72 volts.