Sunday, July 18, 2021

MCQS FOR MODULATION AND DEMODULATION USEFUL FOR B.Sc. STUDENTS


    
1.    
Modulation in which -

(a)    Some characteristics of carrier wave in accordance with intensity of the signal.

(b)    Signal is modified using carrier wave

(c)    carrier wave provide energy to signal

(d)    none of these

Ans.    (a)

2.    Modulation is done –

            (a)   in receiver                      

            (b) transmitter                       

            (c)  in receiver as well in transmitter

(d)    in amplifier

Ans. (b)

            3.     In India the modulation used in radio transmission is –

(a)   phase modulation                         

(b)  frequency modulation

(c)   amplitude modulation                   

(d) none of the above

Ans. (c)

              4.      In amplitude modulation useful power is contained in-

(a)   Carrier                            

(b)  side bands                                

(c) signal                         

(d) Both in carrier and sidebands

Ans. (b)

            5.     In amplitude modulation characteristics of carrier which changes in accordance with signal                     strength is –

(a)   frequency                          

(b)  phase                                     

(c) amplitude                  

(d) frequency and amplitude

Ans. (c)

            6.     Over modulation causes –

(a)   weakening of the signal

(b)   Strengthening of the signal

(c)   excessive power in carrier

(d)   distortion

Ans.   (d)

            7.     100%modulation may be achieved if –

(a)   signal amplitude is less than that of carrier

(b)   signal amplitude is greater than that of carrier

(c)   signal and carrier amplitudes are equal

(d)   modulator is efficient

Ans. (c)

8.    An A.M. wave is expressed as-

            V=5(1+0.6Cos6280t)Sin211× 104 t volts

            the frequencies of lower and upper side band will be –

(a)   335 KHz and 337 KHz                                                 

(b)  336KHz and 337 KHz 

(c) 628KHz and 211KHz                                              

(d) 314KHz and 422KHz

Ans. (a)

            9.     If modulation factor (m) is for an an AM wave. percentage of total power of the wave contained             in side bands is

(a)   25%                       

(b) 40.5%                    

(c) 50%                       

(d) 33.3%

Ans. (d)

            10.     When modulating signal control the frequency of the carrier the resulting wave is –

(a)   amplitude modulated

(b)   phase modulated

(c)   frequency modulated

(d)   none of the above

Ans. (c)

            11.     Modulation is related to a low frequency signal controlling the-

(a)   amplitude of  the carrier

(b)   frequency of the carrier

(c)   phase of the carrier

(d)   any of the above

Ans. (d)

            12.     In a frequency modulated wave frequency deviation is 50KHz and modulation frequency is                 5KHz  modulation index (ms)  is –

(a)   5                            

(b)10                           

(c)15                           

(d)15

Ans. (b)

           13.     Band width required to transmit an audio signal of 2KHz.The carrier frequency  is 500 KHz is -

(a)   4KHz                    

(b) 496khz                              

(c) 504KHz                  

(d)  502KHz

Ans. (a)

14.     Derive  which separate out the signal from modulation the signal form modulated wave is-

(a)   transmitter            

(b) detector                             

(c) filter                 

(d)amplifier

Ans. (b)

            15.     Amplitude of a carrier is mode to vary between 150and 40V. The modulation factor is-

(a)   0.3                         

(b)0.6                          

(c) 0.55                        

(d) 0.65

Ans. (b)


Sunday, July 11, 2021

MCQS Nuclear Instuments (Particle Accelerator) Useful For B.Sc. 3rd, M.Sc. Entrance, PGT, IIT, NEET, JAM And Different University Exams


 Particle Accelerators-

A particle accelerator is a machine for increasing the kinetic energy of electrically charged particles.

Types of particle accelerators-

There are three types of accelerators

i.                Static Accelerator

ii.             Linear Accelerator

iii.           Circular Accelerator

Here our attention is focused on only Circular accelerator.

Circular Accelerator-

There are seven types of circular accelerators-

1. Cyclotron (Fixed Frequency Cyclotron)

It is used for acceleration of positive charge particles like protons, deutrons, alpha particles etc.

It based on the principle of Magnetic Resonance. 

2. Synchro-Cyclotron (Frequency Modulated Cyclotron)

3. Betatron

It is used for acceleration of electrons (beta particles).

It employed no electric field.

It employed changing magnetic field which produce an induced e.m.f. which is responsible for the acceleration of electrons. 

4. Electron Cyclotron

5. Proton Cyclotron

6. Alternating Gradient Cyclotron

7. Omnitron

Geiger-Muller Counter-

It based on the principle that gases becomes electrical conductors due to ionization produced by their exposure to radioactive or nuclear radiation.

MCQS

1: The angular frequency of a cyclotron is independent of

(a) Speed                                             

(b) Mass

(c) Magnetic field                               

(d) Charge

Answer: (a)

2: The maximum kinetic energy of the positive ion in the cyclotron is

(a) qBR2/2m                                           

(b) q2B2R2/2m

 (c) q2B2R2/m                                          

(d) qBR/m

Answer: (b)

3: Cyclotron cannot accelerate

(a) Electrons                                             

(b) Neutrons

(c)  Positive ions                                        

(d) Both (a) and (b)

Answer: (d) Both (a) and (b)

4: The cyclotron frequency of an electron grating in a magnetic field of 1 T is approximately

(a) 28 MHz                                                  

(b) 280 MHz

(c)  2.8 GHz                                                 

(d) 28 GHz

Answer: (d) 

5: Suppose a cyclotron is operated at an oscillator frequency of 12 MHz and a dee radius of 53cm. What is the resulting kinetic energy of the deuterons?

(a)  16.6 MeV                                                

(b) 12 MeV

(c)  15 MeV                                                   

(d) 14 MeV

Answer: (a) 

6: Cyclotron can be used in

(a)  Particle therapy to treat cancer

(b)  Source of high energy beam for a nuclear physics experiment

(c)  Produce short-lived positron-emitting isotopes for PET imaging

(d)  All the above

Answer: (d)

7: A proton of energy 100 eV is moving perpendicular to a magnetic field  T. The cyclotron frequency of the proton in radian/sec

(a) 2.80 x 106                                       

(a) 9.6 x 103

(c)  5.6 x 106                                        

(d) 1.76 x 106

Answer: (b)

8: A cyclotron can accelerate

(a)  β particles                                     

(b) α particles

(c)  High-velocity gamma rays          

(d) High-velocity X-rays

Answer: (b)

9: Which of the following is preferred for accelerating electrons?

(a)  Betatron                                              

(b) Cyclotron                   

(c)  Synchrotron                                        

(d) None of above

Answer: (b)

10: How much pressure is in metal chamber of Geiger Muller Counter?

(a)  100 atm                                           

(b) 0.1 atm

(c) 10 atm                                               

(d) 1 atm

Answer: b

11: Which of the following is cyclic accelerator?

 (a) betatron                                                   

(b) synchrocyclotron

(c) synchrotron                                              

(d) all of these

Answer: d

12: Which of the following accelerate the particles in cyclotron?

 (a) Electric field                                        

(b) Magnetic field

(c) Both (a) and (b)                                    

(d) None of these

Answer: a

13: Which of the following deflects the particle in cyclotron?

 (a) Electric field                                         

(b) Magnetic field

(c) None of these                                         

(d) Both (a) and (b)

Answer: b

14: Betatron works on the principle of

(a) Superposition                                       

(b) Ampere’s law

(c) electromagnetic induction                   

(d) self-induction

Answer: c

15: In betatron, the electron moves in orbit

(a) of constant radius                          

(b) of variables radius

(c) of radius as r2                                  

(d) of radius as  (1/2)r

Answer: a

16: In Betatron, the electrons are injected during

(a) decreasing magnetic field                    

(b) peak magnetic field

(c) increasing magnetic field                     

(d) zero magnetic field

Answer: c

17: The vacuum chamber are coated with silver to

(a) avoid any insulation                              

(b) avoid eddy currents

(c) increase the conductivity                      

(d) none of these

Answer: b

18: For proton acceleration up to 30 GeV, which of the following is used?

(a) Cyclotron                                                      

(b) Betatron

(c) Betatron                                                        

(d) Cosmotron

Answer: d

19: In synchrocyclotron, the frequency is

(a) varied                                                   

(b) kept constant

(c) varies as q 2                                         

(d) varies as r 2

Answer: a

20: ‘When nuclear radiations pass through the counter, gas ionization is produced.’ This is the principle of which of the following detectors?

(a) Proportional counter                        

(b) Flow counter

(c) Geiger Muller counter                      

(d) Scintillation counter

Answer: c

Explanation: ‘When nuclear radiations pass through, gas ionization is produced.’ This is the principle of which of Geiger Muller counter. It is used to measure the intensity of radioactive radiation.

21: Which of the following acts as quenching gas in G.M. counter?

(a) Alcohol                                           

(b) Argon gas

(c) Krypton                                           

(d) Hydrogen

Answer: a

Explanation: Alcohol acts as quenching gas in G.M. counter. It is present in a gas tight envelope along with the electrodes.

22: Which of the following acts as ionising gas in Geiger Muller (G.M.) counter?

(a) Alcohol                                              

(b) Argon gas

(c) Krypton                                             

(d) Hydrogen

Answer: b

Explanation: Argon gas acts as an ionising gas in G.M. counter. It is present in a gas type envelope along with the electrodes.

23: Geiger counter is a device to detect

(a) Mass                                                    

(b) Momentum

(c) Charge                                                

(d) Radiation

Answer: d

24: Normally G. M. counter uses potential different of

(a) 10 Volt                                               

(b) 100 Volt

(c) 1000Volt                                             

(d) 5000Volt

Answer: c

25: Giger- Muller counter detects

(a) Photons

(b) Neutrons

(c) Alpha Particles

(d) All the above

Answer: c

Good Opportunity