How do diodes work gcse

How do you check a diode? The Diode Test procedure is conducted as follows:. Make certain a all power to the circuit is OFF and b novoltage exists at the diode. Voltage may be present in the circuitdue to charged capacitors. Turn the dial rotary switch to Diode Test mode. Connect the test leads to the diode. Reverse the test leads. Peipei Lehnhardt Reviewer. What is diode characteristics? Diode Characteristics.

A diode is simply aPN junction, but its applications are extensive in electroniccircuits. Three important characteristics of a diode are, first of all, the forward voltage drop. Under a forward biascondition, this should be about. Then there is the reversevoltage drop. Rishikesh Kasa Reviewer.

What is meant by Zener diode? A Zener diode is a type of diode thatallows current to flow not only from its anode to its cathode, butalso in the reverse direction, when the Zener voltage isreached. Normal diodes break down with a reverse voltage,but the voltage and sharpness of the knee are not as well defined as for a Zener diode. Yulen Pechenin Reviewer.

How is AC converted to DC? A rectifier is an electrical device that converts alternating current AC , which periodically reversesdirection, to direct current DC , which flows in only onedirection. The process is known as rectification, since it"straightens" the direction of current. Camino Palam Reviewer. What happens if you put a diode in backwards?

But if you reverse the voltage direction,applying the positive side to the cathode and the negative side tothe anode, current doesn't flow. In effect, the diode becomes an insulator. The electricity is flowing to and fro. Putting the current through a diode has the result seen on the right. The positive part of the cycle in unaffected, but the negative is wiped out.

The current goes positive, zero, positive. A thermistor is a just a resistor whose resistance depends on temperature. Most thermistors have lower resistance when the temperature is high. They are used in circuits which are temperature dependent. For example, fire alarms, the temperature gets too high; the alarm sounds. A light dependent resistor is a resistor whose resistance depends on the amount of light shining on it. Its resistance gets less the more light shines on it. It can be used in circuits that are light dependent.

Diodes are used in electric circuits to protect electrical equipment. In electrical equipment such as radio or computers damage can be caused if the battery is connected the wrong way round. Like a resistor, the diode has only two connectors. One is called the anode it is connected to the positive terminal of the power supply , and the other is called the cathode it is connected to the negative terminal of the power supply.

The diagram bon the right shows drawings of different types of diodes and their electronic symbol. When alternating voltage is applied across a diode, it will convert the alternating current AC , which flows back and forth, to direct current DC , which flows only in one direction - but it only does that for half of the cycle - we say it rectifies the current.

It only allows half of the current signal to get though. A capacitor can then be used to smooth the signal - but that is beyond the realms of GCSE!

A light-emitting diode LED that emits more light energy than it consumes in electrical energy has been unveiled by researchers in the US. The possibility of such a device was first predicted in , but a practical version had proved impossible to create until now.

Potential applications of the phenomenon include energy-efficient lighting and cryogenic refrigeration.