RESISTANCE

The electrical resistance is a measure of opposition of flow current through a object. While resistor is a component which is used to provide the resistance in a circuit.

RESISTOR

A resistor is a passive electronic component having two-terminal that implements electrical resistance as a circuit element. Its SI unit is ohm (Ω).

Resistor Symbol
Symbol – Resistor

In electronic circuits, resistors are used to adjust signal levels, reduce current flow, voltage drop, to divide voltages (voltage divider circuit), bias active elements, and terminate transmission lines etc.

When resistor used in series circuit, current flowing through each resistor is equal but the voltage present across each resistor is only part of the total circuit voltage.

HOW DOES A RESISTOR WORK?

Actually resistor converts electrical energy into heat, which is then dissipated into the atmosphere. That’s why when resistor is placed under a voltage it generates heat; don’t try to touch them in high voltage circuits but carefully can be checked by hands with 5V.

WHAT IS THE MAIN FUNCTION OF A RESISTOR IN A CIRCUIT?

The main function of resistors in a circuit is to control the flow of current and dropping the voltage. For example; take an LED (light emitting diode) require 2V and 10mA current, if 5V voltage & 100mA current flows through an LED will damage the LED. So a resistor is used to limit the current and dropping voltage.

Resistance depends on the resistivity of the material. The resistivity of the air is 1.3 × 10^16 to 3.3 × 10^16 Ω-m at 200° C. With no ions in the gas and/or in water its resistance is infinity. So, the resistance of any gaseous material or water depends on the ion content of that.

HOW TO FIND RESISTANCE OF RESISTOR

FIND RESISTANCE USING MULTI-METER

Rotate the multi-meter knob over resistance, as resistor has no polarity connect red wire to one terminal and black to another, this will show you the resistance of the resistor.

Resistance measurement
Resistance measurement

If it shows 1 in multi-meter, that mean this is not in the range you selected, now rotate the knob towards different range shown in multi-meter then you able to check on the screen.

FIND RESISTANCE BY ITS COLOUR CODE

Resistance Colour Code
Colour Code
TO LEARN COLOUR CODE
a) Mnemonic : Big Boys Race Our  Young Girls But Violet Generally Wins
b) First write from bottom to top VIBGYOR eliminate I, then write black (B) at top and white (W) at bottom. Then brown colour (B) (dark colour) under black and grey (G) above white.

 

Color Code for Resistance
Color Code

 


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