# When Should I Use A Resistor?

## Why would you use a resistor?

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.

In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses..

## Should I put a resistor before or after the LED?

Here’s the thing… It doesn’t matter! The resistor can go before – or after – the LED, and it will still protect it. You see.. the current that flows out of a battery is always equal to the current that flows back in to the battery.

## What type of resistor should I use?

A rule of thumb is to find a resistor with twice the power rating. Here I would choose a 250 mW resistor since those are the most standard ones. Usually, you can just use the cheapest resistor you can find with the correct power rating.

## What happens if you don’t use a resistor with an LED?

If you don’t put a resistor in series with the LED and you apply power, the current through the LED will exceed its rating and it will be destroyed. You can use the following equation to solve for R. Vdiode is the diode’s forward turn on voltage.

## Do resistors go on positive or negative side of LED?

Since this resistor is only being used to limit current through the circuit, it can actually be located on either side of the LED. Placing the resistor on the positive (anode) side of the resistor will have no differing effects from placing the resistor on the negative (cathode) side of the LED.

## What does a resistor limit?

Resistor is like a current limiter. It limits the amount of current flowing through a device. … This resistance will create a voltage drop (reduces voltage in that area or drops potential) thus reducing the current passing through it.

## What does R mean in resistors?

Resistor’s Characteristics Resistors have the symbol on the right. Resistance is defined as the voltage developed across the resistor per ampere of current through the resistor. Resistance has a symbol of R measured in unit called Ohm which has a symbol Ω.

## What resistor do I need to reduce voltage?

To reduce voltage in half, we simply form a voltage divider circuit between 2 resistors of equal value (for example, 2 10KΩ) resistors. To divide voltage in half, all you must do is place any 2 resistors of equal value in series and then place a jumper wire in between the resistors.

## Why do you need a resistor in an RC circuit?

The other important part of an RC circuit is the ‘R’ – the resistor. In an electrical circuit, a resistor passively opposes the flow of current. In other words, it ‘resists’ the electron flow moving through the circuit.

## Why do you need a resistor for LED?

Resistors in Light Emitting Diode (LED) Circuits An LED (Light Emitting Diode) emits light when an electric current passes through it. … The ballast resistor is used to limit the current through the LED and to prevent that it burns. If the voltage source is equal to the voltage drop of the LED, no resistor is required.

## How do you know if a resistor is bad?

Set a digital multimeter for “ohms.” Set an ohms range that is equal to or higher than the value of the resistor to be tested. Touch the red lead from the meter to one side, and the black lead to the other. Resistors do not hold a polarity, so it doesn’t matter which side gets the red or black lead.

## What can I use instead of a resistor?

All electrically conductive materials are somewhat resistive, too. Because of this, even a good electrical conductor, such as metal wire, can be used as a resistor.

## How do I know what resistor to use with LED?

Determine the voltage and current needed for your LED. We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/. 010=860 ohms.

## What are the 4 types of resistors?

The types of resistors include:Carbon Composition Resistor.Thermistor.Wire Wound Resistor.Metal Film Resistor.Carbon Film Resistor.Variable Resistor.Varistor﻿Light Dependent Resistor.

## Does it matter where a resistor is placed?

It does not matter which side of the LED the resistor is on. Also, if you have multiple LEDs in series, you only need one current limiting resistor, and it can be placed anywhere in the chain. In general (that is, almost always) the location of a component in a series connection does not matter.