CBSE 12th Standard Physics Subject Semiconductor Electronics Materials Devices And Simple Circuits Value Based Questions 5 Mark Questions With Solution
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CBSE 12th Standard Physics Subject Semiconductor Electronics Materials Devices And Simple Circuits Value Based Questions 5 Mark Questions With Solut
12th Standard CBSE
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Reg.No. :
Physics
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\(p-n\) junction is a semiconductor diode.It is obtained by bringing \(p-\) type semiconductor include contact with \(n-\) type semiconductor. A thin layer is developed at the \(p-\) junction which is devoid of any charge carrier but has immobile ions. It is called depletion layer. At the junction a potential barrier appears, which does not allow the movement of majority charge carriers across the junction in the absence of any biasing of the junction.
\(p-\)n junction offers low resistance when forward biased and high resistance when reverse biased. Read the above paragraph and answer the following questions:
(i) Can we measure the potential barrier of \(p-n\) junction by putting a sensitive voltmeter across its terminals?
(ii) What practical lesson do you draw from the above study?(a) -
Kritika Singh was enjoying TV programme at her home with her younger brother Surya at night. Suddenly, the light went off causing darkness all over. Surya asked her to bring candle along with matchstick to put the TV switch OFF. Kritika at once picked the mobile phone and pressed the button lighting up the surrounding. Her younger brother was surprised and asked, where the light was coming. Kritika proudly showed her mobile.
Read the above passage and answer the following questions:
(i) Which value is displayed by Kritika?
(ii) Name the material used in the formation of LED.
(iii) LED works, in which biasing?(a) -
Ashwin was given 3 semiconductors A, B, and C with respective band gaps of 3 eV, 2 eV and 1 eV for use in a photodetector to detect \(\lambda =1400\quad nm.\) He found that the photodetector was not working with these semiconductor and did not know. Why? his friend Akash found out the reason for it and explained it to him. Read the above passage and answer the following questions:
(i) Why did the photodetector not work?
(ii) What according to you are the values shown by Akash?(a) -
Shorya usually enjoyed loud music. One day his music system was not producing very loud sound. Shorya gets disappointed. He discussed his problem with his big brother Kamal. Kamal advised him to connect an amplifier in series with the amplifier of the stereo system. This increased the sound of Shroya's music system considerably. Read the above passage and answer the following questions:
(i) Which value is displayed by Kamal?
(ii) Why the loudness of music system get increased on connecting amplifier?
(iii) Give the equation for current gain in the transistor as an amplifier.(a) -
Khusbhu Mowar is an electronic engineer. She was working in a project for college exhibition. Her younger sister asked Khushubu about a small black coloured device. which Khusbhu was working on. She clearly explained the working of integrated circuit(IC) to her sister. Read the above passage and answer the following questions:
(i) What according to you, are the values displayed by Khusbhu?
(ii) What is an integrated circuit? What are the uses of the integrated circuit?
(iii) What do you mean by microprocessor?(a)
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CBSE 12th Standard Physics Subject Semiconductor Electronics Materials Devices And Simple Circuits Value Based Questions 5 Mark Questions With Solut Answer Keys
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(i) We cannot measure the potential barrier of \(p-n\) junction by putting a sensitive voltmeter across its terminals because there are no free electrons or holes in the depletion layer. And in the absence of forward biasing, the depletion layer offers infinite resistance.
(ii) From the above study,we find that when some move supports the tendency of majority of the people, the resistance/(opposition) is lowered and output current (desired result) is large (appreciable) However, when some move is against the tendency of majority of people, it suffers rough weather. -
(i) Kritika is a creative and intelligent girl. She has good knowledge of Physics.
(ii) The semiconductor material is used in the formation of LED.
(iii) LED works in forward biasing i.e. n-type is connected to a negative terminal of the battery and p-type is connected with positive terminal of the battery. -
(i) Energy related to wavelength \(\lambda \) is
\(E=\frac { hc }{ \lambda } =\frac { 6.634\times { 10 }^{ -34 }\times 3\times { 10 }^{ 8 } }{ 1400\times { 10 }^{ -9 } } =1.42\times { 10 }^{ -19 }J\)
\(\\ E=\frac { 1.42\times { 10 }^{ -19 } }{ 1.6\times { 10 }^{ -19 } } =0.88eV\ \ [\therefore 1eV=1.6\times { 10 }^{ -19 }J]\)
The photodetector does not work because the energy related to wavelength, 0.8eV is less than band gaps of semiconductor A, B, and C.(ii) The value of Akash are:
(a) helping tendency.
(b) presence of mind.
(c) high degree of awareness.
(d) concern for his friend. -
(i) Kamal is caring for his younger brother. He is an intelligent boy.
(ii) On connecting two amplifiers in series, its amplification gain gets multiplied. Hence, the loudness of music system increases.
(iii) Current gain in the transistor as an amplifier is given by
\({ \beta }_{ AC }=\frac { \triangle { I }_{ C } }{ \triangle { I }_{ B } } \)
where \(\triangle { I }_{ C }\) = change in collector current
\(\triangle { I }_{ B }\) = change in base current. -
(i) Khusbhu is intelligent, cooperative and has good knowledge of electronic devices.
(ii) An integrated circuit is a small device in which different components of electronics circuits such as a diode, transistor, resistors, inductor, etc., are fabricated together in a small chip.
Since it can operate a wide range of functions simultaneously it is used in computer, television, cars, CD players, cell phones, etc.
(iii) The microprocessor is an IC that process all information in a computer.
