The light emitting diode is a heavily doped pn junction with forward bias.

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A light-emitting diode (LED) is a type of semiconductor device that emits light when an electric current flows through it in the forward direction. The LED is a heavily doped p-n junction diode, which means that the doping concentration of impurities in the p-type and n-type regions is much higher than in a regular diode. This high doping level ensures that there is a large number of charge carriers (electrons and holes) available to participate in the conduction process, which allows for efficient light emission.

When a forward bias voltage is applied to the LED, the free electrons in the n-type region move towards the p-type region, while the holes in the p-type region move towards the n-type region. As the electrons and holes move across the p-n junction, they recombine and release energy in the form of light. This process is known as electroluminescence, and the color of the light emitted depends on the energy bandgap of the semiconductor material used to make the LED.

The heavily doped p-n junction in an LED also means that the depletion region is very narrow, which allows for efficient carrier injection and recombination. Additionally, the doping concentration of impurities can be carefully controlled during the fabrication process to tune the energy bandgap and emission wavelength of the LED.

LEDs are widely used in a variety of applications, including lighting, displays, and communications. They are more energy-efficient and longer-lasting than traditional incandescent light bulbs and have a lower environmental impact.

Light Emitting Diode

Light Emitting Diode

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CBSE CLASS XII Related Questions

1.
Read the following paragraph and answer the questions that follow.
A p-type or n-type semiconductor can be converted into a p-n junction by doping it with suitable impurity. The motion of majority charge carriers causes diffusion current across the junction while the barrier electric field causes motion of minority carriers for drift current. In case of unbiased diode, the diffusion and drift currents are equal. This equilibrium is disturbed by the biasing batteries. Diodes, therefore, allow currents in one direction. This property of diode is used in making rectifiers.

2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

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3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

4.
Write two advantages of reflecting telescope over refracting telescope.

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5.
Two air-filled capacitors of capacitances $C_1$ and $C_2$ are connected in parallel with a dc battery. After the capacitors are fully charged, a slab of dielectric constant K is inserted between the plates of each capacitor. How will the (i) charge on each capacitor and (ii) energy stored in the capacitor affected after the slab is introduced.

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6.
An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.

The light emitting diode is a heavily doped p-n junction with forward bias.

CBSE CLASS XII Related Questions

2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

4.
Write two advantages of reflecting telescope over refracting telescope.

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The light emitting diode is a heavily doped p-n junction with forward bias.

CBSE CLASS XII Related Questions

2.Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3.A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

4.Write two advantages of reflecting telescope over refracting telescope.

Comments

SUBSCRIBE TO OUR NEWS LETTER

2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3.
A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.

4.
Write two advantages of reflecting telescope over refracting telescope.