Why does a resistor needs to be placed before a LED?

Why does a resistor needs to be placed before a LED?

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 excess current that can burn out the LED. If the voltage source is equal to the voltage drop of the LED, no resistor is required.

What happens concerning the power at a resistor in series with an LED?

Limiting current into an LED is very important. An LED behaves very differently to a resistor in circuit. Resistors behave linearly according to Ohm’s law: V = IR. For example, increase the voltage across a resistor, the current will increase proportionally, as long as the resistor’s value stays the same.

Why happens if we don’t use a resistor while making an LED glow?

When hooking up an LED, you are always supposed to use a current-limiting resistor to protect the LED from the full voltage. If you hook the LED up directly to the 5 volts without a resistor, the LED will be over-driven, it will be very bright for a while, and then it will burn out.

Where does the resistor go on an 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 causes voltage to fluctuate?

Voltage fluctuations are generally caused by loose or corroded connections at either the house or on the power lines, and are often noticed by flickering lights. Problems related to quality of power supply can be experienced as voltage fluctuations, power surges and spikes.

Can you reduce voltage with a resistor?

The short answer is “don’t do that.” The voltage dropped by a resistor is given by Ohm’s Law: V = I R. So if you know exactly how much current your device will draw, you could choose a resistor to drop exactly 7.5 V, and leave 4.5 V for your device, when that current is run through it.

Does resistor placement matter?

It doesn’t matter which direction you are going, you will have to slow down anyway. Or think about water modeling of electrical circuits. In that model, a resistor is a narrower pipe that slows the flow of water down. Again it does not matter which way you connect the pipe, the same effect will apply.