12th physics chapter 15: full solution, notes, MCQ, & free PDF | Bihar board

1. Which frequency range is used for TV transmission ? 

• • (A) 30 HZ – 300 Hz
  • (B) 30 KHZ – 300 kHZ
  • (C) 30 MHz – 300 MHz
  • (D) 30 GHz – 300 GHZ

Answer : (C) 30 MHz – 300 MHz

2. Sky wave communication is based upon : 

• • (A) reflection by ionosphere
  • (B) absorption by ionosphere
  • (C) transmission through ionosphere
  • (D) none of these

Answer : (A) reflection by ionosphere

3. The loss of strength of a signal while propagating though a medium is known as : 

• • (A) reception
  • (B) absorption
  • (C) transmission
  • (D) attenuation

Answer : (D) attenuation

4. The process of increasing the strength of a signal using an electronic circuit is called :

• • (A) amplification
  • (B) modulation
  • (C) demodulation
  • (D) transmission

Answer : (A) amplification 

5. Modem is a device which performs : 

• • (A) modulation
  • (B) demodulation
  • (C) rectification
  • (D) modulation and demodulation

Answer : (D) modulation and demodulation 

6. The mode of propagation used by short wave broadcast services is : 

• • (A) space wave
  • (B) sky wave
  • (C) ground wave
  • (D) both ‘A’ and ‘C’

Answer : (B) sky wave

7. Large bandwidth for higher data rate is achieved by using : 

• • (A) high frequency carrier wave
  • (B) high frequency audio wave
  • (C) low frequency carrier wave
  • (D) low frequency audio wave

Answer : (A) high frequency carrier wave

8. Who invented world wide web? 

• • (A) J.C.R. Licklider
  • (B) Tim Berners-Lee
  • (C) Alexander Graham Bell
  • (D) Samuel F.B. Morse

Answer : (B) Tim Berners-Lee 

9. The device which is a combination of a receiver and a transmitter is : 

• • (A) Amplifier
  • (B) Repeater
  • (C) Transducer
  • (D) Modulator

Answer : (B) Repeater

10. Which of the following is not a transducer ? 

• • (A) Loudspeaker
  • (B) Amplifier
  • (C) Microphone
  • (D) All of these

Answer : (B) Amplifier

11. Which of the following is an example of broadcast mode of communication?

• • (A) Radio
  • (B) Television
  • (C) Mobile
  • (D) Both A and B

Answer : (D) Both A and B

bihar board most important mcq solution 12th physics chapter 15

12. The waves that are bent down by the ionosphere are:  

• • (A) ground waves
  • (B) surface waves
  • (C) space waves
  • (D) sky waves

Answer : (D) sky waves

13. Who undertook the first space walk and in which year? 

• • (A) Leonov, 1965
  • (B) Neil Armstrong, 1969
  • (C) Rakesh Sharma, 1998
  • (D) None of these

Answer : (A) Leonov, 1965 

14. The term used to collect the information about an object and a place without physical contact” is called :

• • (A) modulation
  • (B) communication
  • (C) amplification
  • (D) remote sensing

Answer : (D) remote sensing

15. The velocity of electromagnetic wave is : 

• • (A) 3 x 10⁹ ms^-1 
  • (B) 3 x 10⁶ ms^-1
  • (C) 3 x 10⁸ ms^-1 
  • (D) 3 x 10¹⁰ ms^-1

Answer : (C) 3 x 10⁸ ms^-1 

16. From which layer of atmosphere are radio waves reflected ? 

• • (A) Ionosphere
  • (B) Mesosphere
  • (C) Chromosphere
  • (D) None of the above

Answer : (A) Ionosphere 

17. The modulation index in amplitude modulation : 

• • (A) is always zero
  • (B) lies between 0 and 1
  • (C) lies between 1 and
  • (D) can never exceed 0.5

Answer : (B) lies between 0 and 1

18. The output of a digital computer is an example of : 

• • (A) digital signal
  • (B) analog signal
  • (C) both (A) and (B)
  • (D) neither (A) nor (B)

Answer : (A) digital signal

19. Basically, a communication system is a : 

• • (A) transmitter
  • (B) receiver
  • (C) messenger
  • (D) All of these

Answer : (D) All of these

20. Present day communication systems are : 

• • (A) electrical only
  • (B) electronic only
  • (C) optical only
  • (D) All of the above

Answer : (D) Allof the above

21. Major pa rts of a communication system are : 

• • (A) transmitter and receiver
  • (B) receiver and communication channel
  • (C) transmitter and communication channel
  • (D) transmitter, receiver and communication channel

Answer : (D) transmitter, receiver and communication channel

22. Frequencies in the UHF range normally propagate by means of :

• • (A) Ground wave
  • (B) Sky waves
  • (C) Surface wave
  • (D) Space wave

Answer : (D) Space wave

23. The height of a TV transmission tower at any place on the surface of the earth is 245m. The maximum distance up to which transmission of tower will reach is :

• • (A) 245 m
  • (B) 245 km
  • (C) 56 km
  • (D) 112 km

Answer : (C) 56 km

24. Modulation is of: 

• • (A) 2 types
  • (B) 3 types
  • (C) 4 types
  • (D) 5 types

Answer : (B) 3 types

25. Meaning of ‘FAX’ is : 

• • (A) Full Access Transmission
  • (B) Fascimile Telegraphy
  • (C) Factual Auto Access
  • (D) Feed Auto Exchange

Answer : (B) Fascimile Telegraphy

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Bihar board 12th science stream subjects wise solution

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SL.N.	Subject name with solutions
01	Physics
02	Chemistry
03	Biology
04	Math
05	Hindi
06	English