12th Physics - Book Back Answers - Unit 10 Electronics And Communication - English Medium Guides

  

 

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Tamil Nadu Board 12th Standard Physics - Unit 10: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 10 from the Tamil Nadu State Board 12th Standard Physics textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Unit 10 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 12 students! Prepare well and aim for top scores. Thank you!

I. Multiple choice questions.

1. The barrier potential of a silicon diode is approximately,
a) 0.7 V  

b) 0.3V 

c) 2.0 V 

d) 2.2V

Answer Key:

a) 0.7 V  

 
2. If a small amount of antimony (Sb) is added to germanium crystal,
a) it becomes a p-type semiconductor
b) the antimony becomes an acceptor atom
c) there will be more free electrons than hole in the semiconductor
d) its resistance is increased

Answer Key: 

c) there will be more free electrons than hole in the semiconductor 

  
3. In an unbiased p-n junction, the majority charge carriers (that is, holes) in the p-region diffuse into n-region because of
a) the potential difference across the p-n junction
b) the higher hole concentration in p-region than that in n-region
c) the attraction of free electrons of n-region
d) All of the above

Answer Key: 

b) the higher hole concentration in p-region than that in n-region 

  
4. If a positive half –wave rectified voltage is fed to a load resistor, for which part of a cycle there will be current flow through the load?
a) ${\mathbf{0}}^{\mathbf{°}}\mathbf{-}{\mathbf{90}}^{\mathbf{°}}$

b) ${\mathbf{90}}^{\mathbf{°}}\mathbf{-}{\mathbf{180}}^{\mathbf{°}}$
c) ${\mathbf{0}}^{\mathbf{°}}\mathbf{-}{\mathbf{180}}^{\mathbf{°}}$ 

d) ${\mathbf{0}}^{\mathbf{°}}\mathbf{-}{\mathbf{360}}^{\mathbf{°}}$

Answer Key: 

c) ${\mathbf{0}}^{\mathbf{°}}\mathbf{-}{\mathbf{180}}^{\mathbf{°}}$  

  
5. The zener diode is primarily used as
a) Rectifier 

b) Amplifier
c) Oscillator 

d) Voltage regulator

Answer Key: 

d) Voltage regulator 

  
6. The principle based on which a solar cell operates is
a) Diffusion 

b) Recombination 

c) Photovoltaic action
d) Carrier flow

Answer Key:  

c) Photovoltaic action 

 

7. The light emitted in an LED is due to
a) Recombination of charge carriers
b) Reflection of light due to lens action
c) Amplification of light falling at the junction
d) Large current capacity.

Answer Key: 

a) Recombination of charge carriers 

  
8. The barrier potential of a p-n junction depends on i) type of semiconductor material ii) amount of doping iii) temperature. Which one of the following is correct? 
a) (i) and (ii) only
b) (ii) only
c) (ii) and (iii) only
d) (i) (ii) and (iii)

Answer Key: 

d) (i) (ii) and (iii) 

  
9. To obtain sustained oscillation in an oscillator,

a) Feedback should be positive

b) Feedback factor must be unity

c) Phase shift must be 0 or 2π

d) All the above

Answer Key: 

d) All the above 

   

10. If the input to the NOT gate is A = 1011, its output is
a) 0100 

b) 1000
c) 1100 

d) 0011

Answer Key: 

a) 0100  

  
11. Which one of the following represents forward bias diode?

 

(a) 

(b) 

(c) 

(d) 

 

Answer Key: 

(a) 

 

  

12. The given electrical network is equivalent to 

a) AND gate 

b) OR gate
c) NOR gate 

d) NOT gate

Answer Key: 

c) NOR gate 

  
13. The output of the following circuit is 1 when the input ABC is

a) 101 

b) 100
c) 110 

d) 010

Answer Key: 

a) 101  

  
14. The variation of frequency of carrier wave with respect to the amplitude of the modulating signal is called
a) Amplitude modulation
b) Frequency modulation
c) Phase modulation
d) Pulse width modulation

Answer Key: 

b) Frequency modulation 

  
15. The frequency range of 3 MHz to 30 MHz is used for
a) Ground wave propagation
b) Space wave propagation 

c) Sky wave propagation
d) Satellite communication

Answer Key:  

c) Sky wave propagation

  

II. Short answer questions.

12th Physics

III. Long answer questions. 

12th Physics

IV. Exercises.   

12th Physics