12th|How to differentiate between DIODE, TRANSISTOR, LED, LDR, IC, CAPACITOR and RESISTANCE from mixture?
For identification, appearance and working of each item will have to be considered.
1. A Diode is a two terminal device. It conducts when forward biased and does not conduct when reverse biased. It does not emit light while conducting. Hence, it does not glow.
2. A LED (light emitting diode) is also a two terminal device. It also conducts when forward biased and does not conduct when reverse biased. It emits light while conducting. Hence, it glows.
3. A Transistor is a three terminal device. The terminals represent emitter (E), base (B) and collector (C).
4. An IC (integrated circuit) is a multi-terminal device in form of a chip.
5. A Resistor is a two terminal device. It conducts when either forward biased or reverse biased. (Infact there is no forward or reverse bias for a resistor). It conducts even when operated with A.C. voltage.
6. A Capacitor is also a two terminal device. It does not conduct when either forward biased or reverse biased. When a capacitor is connected to a D.C. source, then multimeter shows full scale current initially but it decays to zero quickly. It is because that initially a capacitor draw a charge.
What is the difference between LDR (Photoresistor) and LED (Light Emitting Diode)?
LDR and LED are both semiconductor-based devices whose operation is associated with light. LED produces light when an electrical current passes through it while the LDR resistance decreases and allows current when light falls on it. Apart from this, they have many other differences between them.
LDR works on the principle of photoconductivity. It is made of photoconductive semiconductor material whose resistance varies inversely with the change in light intensity. There are no or fewer electrons in darkness. When bright light shines on it, the photons in the light pass their energy to the material generating more free electrons that participate in the condition. Thus the resistance of LDR decreases.
There are different semiconductor materials having photoconductive properties. However different material shows response to different wavelengths such as visible, infrared, and ultraviolet light. The material used in the construction of LDR is N-type semiconductors such as cadmium selenide CdSe, Cadmium sulfide CdS, etc.
It is used in light sensing applications such as automatic street lights, solar trackers, object counters, burglar alarms, camera shutter control fire alarms, etc.
Related Post: LDR: Light Dependent Resistor? Construction, Working, Types and Applications
LED
The LED also known as light emitting diode is a type of diode that emits light when an electric current passes through it. It converts electrical energy into light energy. The light can be infrared, visible, and ultraviolet
It is a PN junction diode that radiates light when connected in forward bias. The junction is converted into a transparent epoxy to prevent the junction from contamination as well as radiate light in all directions.
LED works on the principle of Electro-Luminance. According to it, a material emits light when an electric current passes through it. There are certain semiconductors that possess such properties as gallium arsenide, gallium phosphide, and indium phosphide compounds. Different materials emit different color lights.
LED emits light due to electron-hole combination. Electron and hole combine and release energy equal to the band gap energy. The materials that emit light have direct band gap between conduction and valence band. It emits energy equal to the band gap in the form of photons or light. Other semiconductors such as silicon and germanium possess indirect band gaps that release energy in form of heat.
It had two terminals named anode (+) and cathode (-). It must be operated in forward bias. Reverse biasing an LED can permanently damage it.
Comparison between LDR and LED
The following table shows some of the key differences between light emitting diode (LED) and a light dependent resistor (LDR).
12th|How to differentiate between DIODE, TRANSISTOR, LED, LDR, IC, CAPACITOR and RESISTANCE from mixture?
For identification, appearance and working of each item will have to be considered.
1. A Diode is a two terminal device. It conducts when forward biased and does not conduct when reverse biased. It does not emit light while conducting. Hence, it does not glow.
2. A LED (light emitting diode) is also a two terminal device. It also conducts when forward biased and does not conduct when reverse biased. It emits light while conducting. Hence, it glows.
3. A Transistor is a three terminal device. The terminals represent emitter (E), base (B) and collector (C).
4. An IC (integrated circuit) is a multi-terminal device in form of a chip.
5. A Resistor is a two terminal device. It conducts when either forward biased or reverse biased. (Infact there is no forward or reverse bias for a resistor). It conducts even when operated with A.C. voltage.
6. A Capacitor is also a two terminal device. It does not conduct when either forward biased or reverse biased. When a capacitor is connected to a D.C. source, then multimeter shows full scale current initially but it decays to zero quickly. It is because that initially a capacitor draw a charge.
What is the difference between LDR (Photoresistor) and LED (Light Emitting Diode)?
LDR and LED are both semiconductor-based devices whose operation is associated with light. LED produces light when an electrical current passes through it while the LDR resistance decreases and allows current when light falls on it. Apart from this, they have many other differences between them.
LDR works on the principle of photoconductivity. It is made of photoconductive semiconductor material whose resistance varies inversely with the change in light intensity. There are no or fewer electrons in darkness. When bright light shines on it, the photons in the light pass their energy to the material generating more free electrons that participate in the condition. Thus the resistance of LDR decreases.
There are different semiconductor materials having photoconductive properties. However different material shows response to different wavelengths such as visible, infrared, and ultraviolet light. The material used in the construction of LDR is N-type semiconductors such as cadmium selenide CdSe, Cadmium sulfide CdS, etc.
It is used in light sensing applications such as automatic street lights, solar trackers, object counters, burglar alarms, camera shutter control fire alarms, etc.
Related Post: LDR: Light Dependent Resistor? Construction, Working, Types and Applications
LED
The LED also known as light emitting diode is a type of diode that emits light when an electric current passes through it. It converts electrical energy into light energy. The light can be infrared, visible, and ultraviolet
It is a PN junction diode that radiates light when connected in forward bias. The junction is converted into a transparent epoxy to prevent the junction from contamination as well as radiate light in all directions.
LED works on the principle of Electro-Luminance. According to it, a material emits light when an electric current passes through it. There are certain semiconductors that possess such properties as gallium arsenide, gallium phosphide, and indium phosphide compounds. Different materials emit different color lights.
LED emits light due to electron-hole combination. Electron and hole combine and release energy equal to the band gap energy. The materials that emit light have direct band gap between conduction and valence band. It emits energy equal to the band gap in the form of photons or light. Other semiconductors such as silicon and germanium possess indirect band gaps that release energy in form of heat.
It had two terminals named anode (+) and cathode (-). It must be operated in forward bias. Reverse biasing an LED can permanently damage it.
Comparison between LDR and LED
The following table shows some of the key differences between light emitting diode (LED) and a light dependent resistor (LDR).
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