Que- The electrons in conduction band are free to
a. Transport vibrations
b. Transport signals
c. Transport charge
d. Transport impulses
Answer- Transport charge
Que- Which one has the greatest energy gap ?
a. Semi conductor
b. Conductor
c. Metals
d. Non metals
Answer- Non metals
Que- Many of the semi conductors are crystals of the type
a. Face centred cubic
b. Body centred cubic
c. Simple cubic
d. All of the above
Answer- Face centred cubic
Que- With increase in temperature the electrical conductivity of intrinsic semi conductor
a. Decreases
b. Increases
c. Remains same
d. First increases then decreases
Answer- Increases
Que- Holes can exist in
a. Conductors
b. Insulators
c. Semi conductors
d. All of the above
Answer- Semi conductors
Que- On the basis of band theory of solids the semiconductors have
a. A party filled valence band and totally empty conduction band
b. A completely filled valence band a totally empty conduction band and a very wide forbidden band
c. A completely filled valence band a partially filled conduction band and a narrow forbidden band
d. A partly filled valence band a totally empty conduction band and a wide forbidden band
Answer- A completely filled valence band a partially filled conduction band and a narrow forbidden band
Que- In a semiconductors the charge carriers are
a. Holes only
b. Electrons only
c. Electron and holes both
d. All of the above
Answer- Electron and holes both
Que- The net charge on n-type material is
a. Positive
b. Negative
c. Both positive and negative
d. Neutral
Answer- Neutral
Que- Very weak magnetic fields are detected by
a. Squids
b. Magnetic resonance imaging (MRI)
c. Magnetometer
d. Oscilloscope
Answer- Squids
Que- Energy needed to magnetize and demagnetize is represented by
a. Hysteresis curve
b. Hysteresis loop area
c. Hysteresis loop
d. Straight line
Answer- Hysteresis loop area
Que- Electrons present in p-type material due to thermal pair generation are
a. majority carriers
b. minority carriers
c. dual carriers
d. blockers
Answer- minority carriers
Que- Semi-conductors with donor atoms and free electrons belong to the type
a. n
b. p
c. mix
d. any of above
Answer- n
Que- Semi-conductor germanium and silicon are
a. pentavalent
b. trivalent
c. divalent
d. tetravalent
Answer- tetravalent
Que- Acceptor and donor impurities donate
a. n-carriers only
b. p-carriers only
c. p-carriers and n-carriers respectively
d. n-carriers and p-carriers respectively
Answer- p-carriers and n-carriers respectively
Que- p-n junction when reversed biased acts as a
a. capacitor
b. inductor
c. on switch
d. off switch
Answer- off switch
Que- In p-n-p transistor the collector current is
a. equal to emitter current
b. slightly less than emitter current
c. greater than emitter current
d. any of above
Answer- slightly less than emitter current
Que- In n-p-n transistor, p works as
a. collector
b. emitter
c. base
d. any of above
Answer- base
Que- The simplest type of rectification known as half wave rectification is obtained by
a. using a transistor
b. suppressing the harmonics in A . C voltage
c. suppressing half wave of A . C supply by using diode
d. using a Coolidge tube
Answer- suppressing half wave of A . C supply by using diode
Que- Identify the correct statement about minority carriers
a. holes in n-type and free electrons in p-type
b. holes in n-type and p-type
c. free electrons in n-type and holes in p-type
d. free electrons in n-type and p-type
Answer- holes in n-type and free electrons in p-type
Que- Depletion region of a junction is formed
a. during the manufacturing process
b. under forward bias
c. under reverse bias
d. when temperature varies
Answer- during the manufacturing process
Que- The velocity of an oscillating charge as it moves to and fro along a wire is always
a. constant
b. zero
c. changing
d. infinite
Answer- changing
Que- Which one of following band is completely filled in case of conductors?
a. Conduction band
b. Fermi band
c. Valence band
d. Forbidden band
Answer- Conduction band
Que- Which one of the following has the greatest energy gap?
a. insulator
b. conductor
c. semi conductor
d. any of above
Answer- insulator
Que- The value of resistivity for insulator is of the order of
a. 105 ohm metre
b. 106 ohm metre
c. 107 ohm metre
d. 108 ohm metre
Answer- 108 ohm metre
Que- Thermions are
a. protons
b. positrons
c. electrons
d. photons
Answer- electrons
Que- Hole is equivalent to
a. a negative charge
b. a positive charge
c. a neutral particle
d. an electron
Answer- a positive charge
Que- Which one of the following is not a donor impurity?
a. antimony
b. phosphorus
c. aluminium
d. arsenic
Answer- aluminium
Que- Forward current through a semi conductor diode circuit is due to
a. minority carriers
b. majority carriers
c. holes
d. electrons
Answer- majority carriers
Que- In the transistor schematic symbol, the arrow
a. is located on the emitter
b. is located on the base
c. is locate on the collector
d. points form north to south
Answer- is located on the emitter
Que- In full wave rectification the output D . C .voltage across the load is obtained for
a. The positive half cycle of input A . C .
b. The negative half cycle of input A . C .
c. The complete cycle of input A . C .
d. All of the above.
Answer- The complete cycle of input A . C .
Que- The semiconductor diode can be used as a rectifier because _
a. It has low resistance to the current flow when forward biased & high resistance when reverse biased.
b. It has low resistance to the current flow when forward biased.
c. It has high resistance to the current flow when reverse biased
d. Its conductivity increases with rise of temperature.
Answer- It has low resistance to the current flow when forward biased & high resistance when reverse biased.
Que- In half-wave rectification the output D . C .voltages is obtained across the load for
a. The negative half cycle of A . C .
b. The positive half cycle of A . C .
c. The positive and negative half cycles
d. Either positive or negative half of A . C .
Answer- The positive half cycle of A . C .
Que- The device or circuit used for conversion of A . C .into D . C .is called
a. An amplifier.
b. A rectifier
c. Filtering circuit
d. Converter.
Answer- A rectifier
Que- The device used for conversion of D . C .to A . C .is called
a. Converter
b. A rectifier
c. Inverter
d. Oscillator
Answer- Oscillator
Que- The especially designed semiconductor diodes used as indicator lamps in electronic circuits are
a. The switch
b. The light emitting diode
c. The photo diodes
d. Solar cells.
Answer- The light emitting diode
Que- The specially designed semi-conductor diodes used as fast counters in electronic circuits are
a. The light emitting diodes
b. Photo diodes
c. Photo voltaic cell
d. Solar cells.
Answer- Photo diodes
Que- The alternating voltage is an example of
a. A digital waveform
b. An analogue waveform
c. Discrete waveform
d. None at all
Answer- An analogue waveform
Que- The rectangular voltage is an example of
a. An analogue waveform
b. Continuous wave form
c. Electronic waveform
d. A digital waveform
Answer- A digital waveform
Que- The operational amplifier is
a. A high gain amplifier
b. A high-power amplifier
c. A high resistance amplifier
d. A low resistance amplifier
Answer- A high gain amplifier
Que- In a half-wave rectifier the r.m.s. value of the A . C .component of the wave is
a. Equal to D . C .value
b. More than D . C .value
c. Less than D . C .value
d. Zero
Answer- More than D . C .value
Que- To obtain an n-type semiconductor germanium crystal it must be doped with foreign atoms whose valency is
a. 2
b. 3
c. 4
d. 5
Answer- 5
Que- To obtain a p-type semi-conductor Si Crystal must be doped with foreign atoms whose valency is
a. 2
b. 3
c. 4
d. 5
Answer- 3
Que- The operation of a transistor requires
a. That the emitter be heated
b. That the base be heated
c. That the collector be heated
d. None of the above
Answer- None of the above
Que- In forward bias the width of potential barrier
a. Increases
b. Decreases
c. Remains same
d. No effect
Answer- Decreases
Que- The working of transistor as amplifier is similar to
a. Step up transformer
b. Step down transformer
c. Three diodes in common
d. Triode vacuum tube
Answer- Triode vacuum tube
Que- The electronic circuits which implement the various logic operations are called
a. Logic gates
b. Boolean algebra
c. Amplifier gain
d. Logic functions
Answer- Logic gates
Que- An OP-AMP comparator is a circuit that compares the signal voltage on one of its inputs with a _
a. Non-inverting voltage at output
b. Reference voltage on the other
c. Virtual input
d. Output
Answer- Reference voltage on the other
Que- An OP-AMPs can amplify
a. D . C .
b. A . C .
c. Both A . C .& D . C .
d. None of the above
Answer- A . C .
Que- Non-inverting amplifier circuits have
a. A very high input impedance
b. A very low input impedance
c. A low output impedance
d. None of the above
Answer- A very high input impedance
Que- Tick the correct statement
a. the flight path of a vertically falling body appears straight to the stationary observer
b. the flight path of vertically falling body appears parabolic to an observer in uniform relative motion
c. all states of rest and motion are relative and there is no such thing as absolute motion
d. all the above
Answer- all the above
Que- Mark the wrong statement.
a. a frame of reference which is either at rest or moves with a constant velocity is called an inertial frame of reference
b. an un-accelerated frame of reference is called an inertial frame of reference
c. all the frames of reference in uniform rectilinear motion are equivalent
d. Newtons laws of motion are valid in an accelerated (non inertial) frame of reference
Answer- Newtons laws of motion are valid in an accelerated (non inertial) frame of reference
Que- The relativistic energy E is equivalent to relativistic mass given by
a. Ec2
b. E/c2
c. E/c
d. c2/E
Answer- E/c2
Que- An observer shoots parallel to a meter stick at very high (relativistic) speed and finds that the length of meter stick is
a. greater than one meter
b. less than one meter
c. one meter
d. a foolish question
Answer- less than one meter
Que- 0.001 kg mass will be equivalent to
a. 2.50 GWh
b. 25.00 GWh
c. 0.26 GWh
d. 250 GWh
Answer- 25.00 GWh
Que- Which one of the following radiations has the strongest photon?
a. T.V waves
b. micro waves
c. X-rays
d. ?-rays
Answer- ?-rays
Que- Tick the right statement.
a. no photo electronic emission takes place if the frequency of radiation however intense it may be is less than a certain critical value called threshold frequency
b. threshold frequency depends upon the nature of the metal surface
c. maximum energy of a photoelectron is a function of frequency rather than intensity of radiation
d. all of the above
Answer- all of the above
Que- Linear momentum of a photon is
a. zero
b. hv/c2
c. hv/c
d. c2/hv
Answer- zero
Que- A device based on photoelectric effect is called
a. photo sensitive detection
b. photo diode
c. photosynthesis
d. photo cell
Answer- photo cell
Que- The linear momentum of an X-ray photon of wavelength 0.1A is
a. 6.625x1023N-s
b. 66.25x1023N-s
c. 662.5x1023N-s
d. data is insufficient
Answer- 6.625x1023N-s
Que- Stopping potential for a metal surface in case of photoelectric emission depends on
a. the threshold frequency for the metal surface
b. the intensity of incident light
c. the frequency of incident light and work function of the metal surface
d. all of the above
Answer- the frequency of incident light and work function of the metal surface
Que- The existence of Ether wind was experimentally rejected by
a. equal to its rest mass
b. double of its rest mass
c. infinite
d. zero
Answer- infinite
Que- If a material object moves with speed of light its mass becomes
a. equal to its rest mass
b. double of its rest mass
c. infinite
d. zero
Answer- infinite
Que- As the temperature of black body is raised the wavelength corresponding to maximum intensity
a. shifts towards longer wavelength
b. shifts towards shorter wavelength
c. remain the same
d. shifts towards longer as well as shorter wavelengths
Answer- shifts towards shorter wavelength
Que- Rest mass of a photon is
a. infinite
b. zero
c. very small
d. 1.67 x 10-27 kg
Answer- zero
Que- The name of the photon for quantum of light was proposed by
a. Ampere
b. Plank
c. Thomson
d. Einstein
Answer- Einstein
Que- In Compton scattering the change in wave length is max if
a. angle of scattering is 90 Degree
b. angle of scattering is 60 Degree
c. angle of scattering is 180 Degree
d. angle of scattering is zero
Answer- angle of scattering is 180 Degree
Que- Davison Germer experiment indicates
a. interference
b. polarization
c. election diffraction
d. refraction
Answer- election diffraction
Que- A photon is
a. a unit of energy
b. a positively charged particle
c. a quantum of electromagnetic radiation
d. a unit of wavelength
Answer- a quantum of electromagnetic radiation
Que- After traveling through a vacuum a photon of light entering into some transparent denser medium. Thus the energy of light
a. Increases because wavelength decreases
b. Decreases because speed decreases
c. Remains same
d. Increases then decreases
Answer- Remains same
Que- In a photoelectric effect monochromatic light is incident on a metal surface. If the incident light of twice the intensity but of same wavelength the kinetic energy of the emitted electron
a. Becomes double
b. Remains same
c. Becomes half
d. First increases then decreases because curvilinear graph
Answer- Remains same
Que- If the wavelength of incident radiation is increased in photoemission then
a. The maximum kinetic energy of the photoelectrons increases.
b. The minimum kinetic energy of the photoelectrons decreases.
c. The minimum kinetic energy of the photoelectrons increases.
d. The average kinetic energy of the photoelectrons decreases.
Answer- The average kinetic energy of the photoelectrons decreases.
Que- A photon of wave length 900nm behaves like a particle of mass
a. 5.53 x 10-36kg
b. 0 kg.
c. 2.46 x 10-36kg
d. 1.84 x 10-44kg
Answer- 2.46 x 10-36kg
Que- In Davisson-Germer experiment the diffracted proton from crystal shows
a. Particle property
b. Wave property
c. Light property
d. Quantum property
Answer- Wave property
Que- If a diffraction grating is placed in the path of a light beam it reveals
a. Wave property
b. Particle property
c. Energy particle
d. Electromagnetic wave property
Answer- Wave property
Que- In electron microscope we use energetic particles because of
a. Penetrating power is high
b. Kinetic energy is large.
c. Wavelength is very short.
d. All the above reasons.
Answer- Wavelength is very short.
Que- In electron microscope electric & magnetic fields are used as
a. Electromagnetic gun.
b. Source of electromagnetic waves.
c. Deflecting charged particle
d. Converging source of electrons.
Answer- Converging source of electrons.
Que- A three dimensional image is obtained by
a. Electron microscope
b. Seanning electron microscope
c. Magnetic imaging
d. None of the above
Answer- Seanning electron microscope
Que- The uncertainty in momentum & position is due to its
a. Property of matter and radiation.
b. Two dimensional motion.
c. Emission of certain wavelength
d. Very high velocity.
Answer- Property of matter and radiation.
Que- For confinement of electron in a box of radius 10-14m the electron speed should be
a. 107m/sec
b. Should be greater than speed of light.
c. Be zero
d. Not be wavelike.
Answer- Should be greater than speed of light.
Que- The energy radiated is directly proportional to fourth power of Kelvins temperature is
a. Karl-weins law
b. Rayleigh Jeans law.
c. Stephens law.
d. Plancks
Answer- Stephens law.
Que- Compton effect proves the
a. Photon theory of light
b. Dual nature of light
c. Wave nature of light
d. Uncertain nature of light
Answer- Photon theory of light
Que- Electron moves in the orbit as
a. Simple vibratory motion.
b. Standing wave motion.
c. Vibratory motion like up and down.
d. S.H.M like sound.
Answer- Standing wave motion.
Que- Ratio of the weight of H-atom to that of an electron is approximately
a. 18.336
b. 1836
c. 18360
d. 183.6
Answer- 1836
Que- Photon of highest frequency will be absorbed when transition takes place from
a. 1st to 5th orbit
b. 2nd to 5th orbit
c. 3rd to 5th orbit
d. 4th to 5th orbit
Answer- 1st to 5th orbit
Que- In hydrogen spectrum which one of the following series lies in the ultraviolet region?
a. Balmer series
b. Pfund series
c. Bracket series
d. Lymann series
Answer- Lymann series
Que- In obtaining an X-ray photograph of our hand we use the principle of
a. photo electric effect
b. ionization
c. shadow photograph
d. any of above
Answer- shadow photograph
Que- Excited atoms return to their ground state in
a. 10-10s
b. 10-8s
c. 10-6s
d. 10-9s
Answer- 10-8s
Que- When we excite some atoms by heat collision or electrical discharge they will
a. radiate electromagnetic energy with a continuous distribution of wavelength
b. absorb particular wavelengths when white light is incident on them
c. radiate electromagnetic energy of discrete characteristic wavelength
d. emit either invisible or visible light
Answer- radiate electromagnetic energy of discrete characteristic wavelength
Que- Hydrogen atom does not emit X-rays because
a. its energy levels are too close to each other
b. its energy levels are too far apart
c. it is too small in size
d. it has a single electron
Answer- it has a single electron
Que- Which one of following postulate is in accordance with the Rutherfords model?
a. continuous spectra for atoms
b. discrete spectra for atoms
c. either continuous nor discrete
d. no spectrum
Answer- continuous spectra for atoms
Que- X-ray are
a. of unknown nature
b. high energy electrons
c. high energy photons
d. radio isotopes
Answer- high energy photons
Que- Tick the correct statement
a. an atom has limited number of ionization potentials but a large number of excitation potentials
b. there are as many excitation potentials as there are excited states
c. the difference between the energy of the ground sate and any one of the excited states is the measure of excitation energy
d. all of above
Answer- all of above
Que- Total number of series in hydrogen spectrum is
a. three
b. four
c. five
d. six
Answer- five
Que- The radiations emitted form hydrogen filled discharge tube show
a. band spectrum
b. line spectrum
c. continuous spectrum
d. absorption spectrum
Answer- line spectrum
Que- Radiation with wavelength longer than red lights
a. ultraviolet rays
b. X-rays
c. infra red radiation
d. visible radiation
Answer- infra red radiation
Que- Bracket series is obtained when all transition of electron terminate on
a. 4th orbit
b. 5th orbit
c. 3rd orbit
d. 2nd orbit
Answer- 4th orbit
Que- Reverse process of photoelectric effect is
a. pair production
b. Compton effect
c. annihilation of matter
d. X-rays production
Answer- X-rays production
Que- The penetrating power of X-rays depends on their
a. applied voltage
b. frequency
c. source
d. all of the above
Answer- frequency
Que- When X-rays are passed through successive aluminum sheets what happens to their thickness?
a. increases
b. it decreases
c. it remains same
d. sometimes increases and sometimes decreases
Answer- it remains same
Que- Radiation produced from TV picture tube is
a. ?-rays
b. X-rays
c. Far infrared.
d. Infrared
Answer- X-rays