When producing a voltage drop between terminals, it must be in accordance with Ohm’s law.
Ohm’s law states that the potential difference between the two points on a resistor and the current flowing through it must be proportional. The electrical resistance is equal to the voltage drop across the resistor divided by the current through the resister.
The potential difference is also called the voltage drop and may at times be designated by E or U instead of a V.
Resistors are used as part of electrical and electronic networks and should have a section in every installer’s bin.
Resistors are used to create a known voltage to current ratio in an electric circuit.
If the potential difference between two points in a circuit is known, a resistor can also be used to create a known current proportional to that difference.
A resistor placed in a series with another component, such as that of a light-emitting diode, reduced the current to a known safer value.
An attenuator is a network of two or more resistors or a voltage divider.
The higher the value of resistance which is measured in ohms, the lower the current will be.
Resistors are color coded. Look for the color stripe on the resistor indicating which way the current is flowing. The power flows from the end without the stripe to the end with the stripe. Hold the resistor with the stripes to the left. By reading the first three stripes you can determine the capacity (ohms). The first and second stripes are single digits; the third is the number of zeroes that follow the first two numbers. Match the numbers with colors: black – 0, brown – 1, red – 2, orange – 3, yellow – 4, green – 5, blue – 6, violet – 7, gray – 8, white – 9. The fourth stripe indicates the accuracy tolerance: gold = +/-5%, silver = +/-10%, no stripe = +/-20%.
Variable resistors values can be adjusted by turning a shaft or sliding a control.
Potentiometers or rheostats allow the resistance of the device to be changed by hand.
There are some variable resistors that can be fitted with a type of mechanical device to count the turns of the resistor.
The more modern resistors use a plastic material that does not corrode and wears better over time.