# Do you know your resistors?

A resistor is a two terminal component that resists the flow of current. They are a passive component i.e they can only consume power and not generate it. Usually they are used to limit the current flowing through other components. For example If we connect a Light emitting diode (LED), to a battery it would burn outrightly because the battery would allow a large amount of current to flow through the LED, this can be avoided if we put a resistor between the LED and the battery. We can calculate the resistance of a resistor using the Ohm’s law V=IR. Usually we calculate the resistance by reading the color bands of the resistor or by measuring it with a multimeter. Each strip of color on the resistor represents a specific digit. Different colors corresponding to their digit values are shown in the image below

Where:

‘**a’ **represents the 1st significant digit, which is the first band color of resistor.

‘**b’ **represents the 2nd significant digit, which is the second band color of resistor.

‘**c’ **represents the 3rd significant digit, which is the third band color of resistor.

‘**d’ **represents the 4th significant digit, which is the fourth band color of resistor and this is the multiplier value used in formula.

‘**e’ **represents the 5th significant digit, which is the fifth band color of resistor and this is the tolerance value of resistor.

Let’s take an example of a 5-band resistor with the colors brown, green, red, black and gold, according to the formula the resistance will be: 152 * 1 = 152 Ohms with 5% tolerance. In the case of a resistor with four colour bands the third band color gives the multiplier value and the fourth band color represents the tolerance value of the resistor.