Class 12 Physics MCQ

Test your knowledge with important Class 12 Physics MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Class 12 Physics MCQs at Bissoy

• Which among the following can be detected by an envelope detector?
  ক

  Low frequency AM waves

  খ

  Very low frequency AM waves

  গ

  Envelope detectors cannot detect AM waves

  ঘ

  High frequency AM waves
• The rectifier produces the output required in a communication system.
  ক

  True

  খ

  False
• Which one of the following is the process of recovering the modulated signal?
  ক

  Amplification

  খ

  Detection

  গ

  Attenuation

  ঘ

  Transmission
• Which of the following is not part of the detector system?
  ক

  Rectifier

  খ

  Envelope detector

  গ

  Amplifier

  ঘ

  AM wave
• What is the full form of IF?
  ক

  Intermediate frequency

  খ

  Internal frequency

  গ

  Interval frequency

  ঘ

  Immediate frequency
• Which of the following is false?
  ক

  Bandpass filters filter out the unwanted frequencies

  খ

  The transmitting antenna transmits the signal over large distances

  গ

  Attenuation should be reduced for a signal

  ঘ

  The modulated signal is quite strong
• A bandpass filter rejects direct current.
  ক

  True

  খ

  False
• Identify the one that is not required in the process of production of amplitude modulated wave?
  ক

  Square law device

  খ

  Rectifier

  গ

  Bandpass filter

  ঘ

  Combination of message and carrier signal
• Which of the following is true about carrier signal?
  ক

  Carrier signals have low frequency

  খ

  Carrier signals are used to increase the wavelength of the signal

  গ

  Carrier signals have high frequency

  ঘ

  Carrier signals and message signals are the same
• Which one of the following is a way to produce a signal?
  ক

  Superimposition with a carrier signal

  খ

  Superimposition with a received signal

  গ

  Superimposition with a transmitted signal

  ঘ

  No superimposition is required
• Identify the type of modulation where the modulating wave is superimposed on a high-frequency carrier wave.
  ক

  Phase modulation

  খ

  Amplitude modulation

  গ

  Frequency modulation

  ঘ

  Wavelength modulation
• Suggest a possible communication channel for the transmission of a message signal that has a bandwidth of 200kHz.
  ক

  TV transmission

  খ

  Optical fiber

  গ

  AM radio

  ঘ

  FM radio
• How can the noise be reduced in AM signal?
  ক

  Increasing amplitude

  খ

  Increasing wavelength

  গ

  Increasing bandwidth

  ঘ

  Increasing frequency deviation
• PAM stands for pulse attenuation modulation.
  ক

  True

  খ

  False
• Of the following which is the preferred modulation scheme for digital communication?
  ক

  Pulse code modulation

  খ

  Pulse amplitude modulation

  গ

  Pulse position modulation

  ঘ

  Pulse width modulation
• What does AGC stand for?
  ক

  Automatic gain control

  খ

  Automatic gear control

  গ

  Amplitude gain control

  ঘ

  Automotive gear center
• Identify the type of modulation where the frequency of the modulated wave is equal to that of the carrier wave.
  ক

  Frequency modulation

  খ

  Amplitude modulation

  গ

  Carrier modulation

  ঘ

  Phase modulation
• What happens in frequency modulation?
  ক

  The amplitude of the modulated wave varies as the frequency of the carrier wave

  খ

  The frequency of the modulated wave varies as the amplitude of the modulating wave

  গ

  The amplitude of the modulated wave varies as the amplitude of the carrier wave

  ঘ

  The frequency of modulated wave varies as the frequency of modulating wave
• What is the maximum distance up to which a TV transmission can be received if the TV tower has a height of 50 m?
  ক

  28284 km

  খ

  20.8 km

  গ

  28.2 km

  ঘ

  45 km
• Why is AM used for broadcasting in the communication systems?
  ক

  Its use avoids receiver complexity

  খ

  It is more noise immune than other modulation systems

  গ

  It requires less transmitting power

  ঘ

  No other modulation system can give the necessary bandwidth for faithful transmission
• Modulation is a process of the superposing high-frequency audio signal on low-frequency radiowaves.
  ক

  True

  খ

  False
• What happens in a frequency modulated wave?
  ক

  Frequency varies with time

  খ

  Amplitude varies with time

  গ

  Both frequency and amplitude varies with time

  ঘ

  Both frequency and amplitude are constant
• Why audio signals cannot be transmitted directly?
  ক

  The signal has more noise

  খ

  The signal cannot be amplified for distance communication

  গ

  The transmitting antenna length is very small to design

  ঘ

  The transmitting antenna length is very large and impracticable
• Identify the limitation of amplitude modification.
  ক

  The quality of the audio signal is high

  খ

  Amplitude modulation suffers from noise

  গ

  The efficiency of AM transmission is high

  ঘ

  It does not require a wider channel
• What is the modulation used to?
  ক

  Reduce the bandwidth used

  খ

  Separate the transmissions of different users

  গ

  Ensure that intelligence may be transmitted to long distances

  ঘ

  Allow the use of practical antennas
• The phase difference between space current and capacitive displacement current is 0 rad, when radio waves undergo the ionosphere.
  ক

  True

  খ

  False
• What is the physical significance of the Ozone layer in the atmosphere?
  ক

  Stops ultraviolet radiation

  খ

  Stops greenhouse effect

  গ

  Stops increase in temperature of the atmosphere

  ঘ

  Absorbs pollutant gases
• What is the maximum distance upto which the TV transmission can be received, if the TV tower has a height of 220 m?
  ক

  37.75 km

  খ

  20 km

  গ

  59.3 km

  ঘ

  40.55 km
• Identify a suitable frequency for skywave propagation.
  ক

  Upto 2 MHz

  খ

  From 2 MHz to 30 MHz

  গ

  From 2 MHz to 50 MHz

  ঘ

  From 2 MHz to 80 MHz
• The biological importance of the ozone layer is to stop the greenhouse effect.
  ক

  True

  খ

  False