For detecting the light ____.
A) The photodiode has to be forward biased.
B) The photodiode has to be reversed biased.
C) The LED has to be connected in forward biased.
D) The LED has to be connected in reverse biased.
Answer
290.1k+ views
Hint: Light consists of photons as a packet of energy. Current in photodiode changes when the light falling on photodiode with frequency is greater than threshold frequency of photodiode. An LED is a device used to produce light when current is passed through it. Light is detected when there is change in current in the circuit.
Complete step by step answer:
We know that LEDs produce light when current is passed through it and it just produces light energy. Then LED is a type of diode which can never be used to detect light.
Photodiode is a diode, which shows some changes when light falls on it.
In the reversed biased condition of photodiode, the width of the depletion layer increases as the applied reverse biased voltage increases across the diode when light falls on it. So, by applying a large voltage, more of the incident photons are converted into electric current by photodiode and increasing the efficiency.
In forward bias condition of photodiode, the width of depletion layer decreases due to only some part of incident photons being converted into electric current by photodiode and efficiency is less in comparison to reverse biased.
Then, for detecting the light the photodiode has to be reversed biased.
Hence correct answer of option B.
Note: Each photodiode has its fixed threshold frequency for the incident light. If the frequency of photons is less than threshold frequency then the photons of light do not convert into current. Because when light falls on photodiodes, the electrons jump from lower potential to higher potential due to which current produces an electron requiring a photon of minimum energy which is equal to threshold energy. The energy of a photon is directly proportional to frequency of light.
Complete step by step answer:
We know that LEDs produce light when current is passed through it and it just produces light energy. Then LED is a type of diode which can never be used to detect light.
Photodiode is a diode, which shows some changes when light falls on it.
In the reversed biased condition of photodiode, the width of the depletion layer increases as the applied reverse biased voltage increases across the diode when light falls on it. So, by applying a large voltage, more of the incident photons are converted into electric current by photodiode and increasing the efficiency.
In forward bias condition of photodiode, the width of depletion layer decreases due to only some part of incident photons being converted into electric current by photodiode and efficiency is less in comparison to reverse biased.
Then, for detecting the light the photodiode has to be reversed biased.
Hence correct answer of option B.
Note: Each photodiode has its fixed threshold frequency for the incident light. If the frequency of photons is less than threshold frequency then the photons of light do not convert into current. Because when light falls on photodiodes, the electrons jump from lower potential to higher potential due to which current produces an electron requiring a photon of minimum energy which is equal to threshold energy. The energy of a photon is directly proportional to frequency of light.
Last updated date: 31st May 2023
•
Total views: 290.1k
•
Views today: 4.46k
Recently Updated Pages
Most eubacterial antibiotics are obtained from A Rhizobium class 12 biology NEET_UG

Salamin bioinsecticides have been extracted from A class 12 biology NEET_UG

Which of the following statements regarding Baculoviruses class 12 biology NEET_UG

Sewage or municipal sewer pipes should not be directly class 12 biology NEET_UG

Sewage purification is performed by A Microbes B Fertilisers class 12 biology NEET_UG

Enzyme immobilisation is Aconversion of an active enzyme class 12 biology NEET_UG

Trending doubts
Difference Between Plant Cell and Animal Cell

Write an application to the principal requesting five class 10 english CBSE

Ray optics is valid when characteristic dimensions class 12 physics CBSE

Give 10 examples for herbs , shrubs , climbers , creepers

Write the 6 fundamental rights of India and explain in detail

Write a letter to the principal requesting him to grant class 10 english CBSE

List out three methods of soil conservation

Fill in the blanks A 1 lakh ten thousand B 1 million class 9 maths CBSE

Write a letter to the Principal of your school to plead class 10 english CBSE
