The highest value reached by voltage or current in one cycle is called
(A) Peak to peak value
(B) Peak value
(C) Instantaneous value
(D) Root mean square value
In pure resistive A.C. circuit, instantaneous value of voltage or current
(A) Current lags behind voltage
(B) Current leads voltage by
(C) Both are in phase
(D) Voltage leads current by
The most common source of an A.C. voltage is
(A) Motor
(B) Cell
(C) Generator
(D) Thermocouple
The output voltage of a rectifier is
(A) Smooth
(B) Pulsating
(C) Perfectly direct
(D) Alternating
The A.0 circuit in which current and voltage are in phase, the power factor is
(A) Zero
(B) 1
(C) 0.5
(D) Infinity
A detector which can count fast and operated low voltage is
(A) G.M. Counter
(B) Solid state detector
(C) Wilson cloud chamber
(D) bubble chamber
At resonance frequency, the impedance of RLC series circuit is
(A) Zero
(B) Minimum
(C) Maximum
(D) Moderate
The algebraic sum of potential, changes for a closed circuit is
(A) Positive
(B) Negative
(C) Zero
(D) Greater than unity
When the emf in a circuit is zero it draws
(A) Zero current
(B) Maximum
(C) Minimum current
(D) Steady current
The circuit which changes input signals at output with phase shift at 180°C is called
(A) Amplifier
(B) Inverter
(C) Switch
(D) Operational amplifier
The net reactance of a circuit is zero. The circuit may consist of
(A) An indicator only
(B) Capacitor only
(C) Both indicator and capacitor
(D) None
At high frequency, RLC series circuit shows the behaviour of
(A) Pure inductive circuit
(B) Pure resistive circuit
(C) Pure capacitive circuit
(D) Pure RLC circuit
The basic circuit element in A.C. circuit which controls current
(A) Resistor only
(B) Capacitor only
(C) Inductor only
(D) All of these
At high frequency, the current through a capacitor of A.C. circuit will be
(A) Large
(B) Small
(C) Infinite
(D) Zero
The device which allows only the continuous flow of an A.C. through a circuit is
(A) Capacitor
(B) Inductor
(C) D.C. Motor
(D) Battery
In a pure inductive A.C. circuit the current
(A) Lags behind voltage by 90°
(B) Leads the voltage by 90°
(C) In phase with voltage
(D) Leads the voltage by 270°
Which factor does not affect the conductivity of PN-junction diode
(A) Doping
(B) Temperature
(C) Voltage
(D) Pressure
If fingers of right hand show the direction of magnetic field and palm shows the direction of force then thumb points for
(A) Torque
(B) Voltage
(C) Current
(D) Inducted emf
Magnetic field inside a current carrying long solenoid is
(A) Non-unform
(B) Week
(C) Uniform and steady
(D) Zero
If the number of turns become double but length remain same, then magnetic field in the solenoid become
(A) Half
(B) Double
(C) Remain same
(D) Zero
If magnetic field is doubled then magnetic energy density becomes
(A) Four times
(B) Two times
(C) Three times
(D) Six times
A magnetic field acts on a charged particle so as change
(A) speed
(B) Energy
(C) Direction of motion
(D) All of these
Electric current produces magnetic field was suggested by
(A) Faraday
(B) Oersted
(C) Henry
(D) Lenz
The radius of atom is of the order of
(A) 101° m
(B) 10-1° m
(C) 10-14m
(D) 1014 m
Laser can only be produced of a atom is in its
(A) Normal state
(B) Excited state
(C) Ionized state
(D) De-excited state
The number of protons is any atom are always equal to number of
(A) Electron
(B) Neutron
(C) Positron
(D) Mesons
The radius of 3 Bohr orbit in hydrogen atom is greater tlian the radius of 1st orbit by a factor of
(A) 2
(B) 3
(C) 4
(D) 9
The emission of x-rays leave the atom of the target in
(A) Ground state
(B) Excited state
(C) Double ionized state
(D) Single ionized state
Energy of the 4th orbit in hydrogen atom is
(A) —2.51 ev
(B) —3.50 ev
(C) —13.6 ev
(D) —0.85 ev
The residing time of atoms in meta stable in case of laser action is
(A) 10-4S
(B) 10-5S
(C) 10-8S
(D) 10-3S
The capacitive reactance to pure D.C. is
(A) Zero
(B) Infinite
(C) Variable
(D) Equal to inductive reactance
Conversion of A.C. into D.C. is called
(A) Modulation
(B) Amplification
(C) Oscillation
(D) Rectification
The frequency of A.C. source used in Pakistan is
(A) 50 Hz
(B) 60 Hz
(C) 45 Hz
(D) 70 Hz
Which one is not present in A.0 generator?
(A) Armature
(B) Magnet
(C) Slip rings
(D) Commutator
Maximum emf generated in a generator is
(A) co = c sin 0
(B) & = co sin 0
(C) E = N co AB sin 0
(D) co = N (DAB
The principle of an alternating current generator is based on
(A) Coulomb’s law
(B) Ampere’s law
(C) Faraday’s law
(D) Lenz’s law
The component in a generator which consumes electrical energy is called
(A) Capacitor
(B) Load
(C) Split rings
(D) Commulator
The mutual induction plays role in
(A) Generator
(B) Galvanometer
(C) Transformer
(D) D.C. motor
The electric field can deflect
(A) Neutrons
(B) X-rays
(C) R-rays
(D) Rays
The concept of an electric field lines is introduced by
(A) Coulomb
(B) Faraday
(C) Einstein
(D) Joseph Henry
The electric field created by positive charge is
(A) Radially outward
(B) Radially inward
(C) Circular
(D) Zero
The component in a for which consumes electrical energy is called
(A) Capacitor
(B) Split rings
(C) Commulator
Electrical energy is measured
(A) Walt
(B) Horse Power
(C) Kilowatt
(D) Kilowatt hour
Two opposite point charge of same magnitude separated by distance 2d, electric potential mid-way, between them is
(A) 1 V
(B) 2 V
(C) Zero
(D) —V
If the motor is overloaded, then the magnitude of Back error
(A) Increases
(B) Decreases
(C) Constant
(D) Becomes zero
The emission of x-rays leave the atom of the target in
(A) Ground state
(B) Excited state
(C) Double ionized state
(D) Single ionized state
Production of X-rays is reverse process of
(A) Photo-electric effect
(B) Compton effect
(C) Annihilation
(D) Pair production
X-rays are similar in nature to
(A) Alpha rays
(B) Beta rays
(C) Cathode rays
(D) Gamma rays
X-rays photon moves with the velocity of
(A) Light
(B) Less than light
(C) Greater than light
(D) Sound
X-rays can be
(A) Reflected
(B) Diffracted
(C) Polarized
(D) All of these
X-rays are similar in nature to
(A) Alpha rays
(B) Beta rays
(C) Cathode rays
(D) Gamma rays
X-rays are electromagnetic having wavelength in range
(A) 102m
(B) 10m
(C) 10xm
(D) 10-6m
X-rays photon moves with the velocity of
(A) Light
(B) Less than light
(C) Greater than light
(D) Sound
Which is not true for x-rays
(A) X-rays are not deflected by electric field
(B) X-rays are polarized
(C) X-rays consist of electromagnetic waves
(D) X-rays can be diffracted by grating
Which is true for both a-particles and y-rays
(A) They cause ionization in air
(B) They can be deflected by electric field
(C) They can be deflected by magnetic field
(D) They can penetrate a few millimeter of aluminum
The inductance can be increased by winding the wire around a core made of
(A) Copper
(B) Silicon
(C) Iron
(D) Aluminum
The winding of the electromagnet in motor are usually called
(A) Magnetic coils
(B) Field coils
(C) Electric coils
(D) Electric-o-electric coils
Energy density in case of a capacitor is always proportional to
(A) E2
(B) so
(C) V2
(D) C
In case of capacitor the unit of its reactance is
(A) Farad
(B) Ohm
(C) Moh
(D) Henry
In a capacitor energy is stored in the
(A) Magnetic field
(B) Electric field
(C) Gravitational field
(D) Nuclear field
Number of electrons emitted in photoelectric effect depends upon
(A) Intensity of incident light
(B) Frequency of incident light
(C) Energy of incident light
(D) Wavelength of incident light
Free electrons are
(A) Tightly bound
(B) Fixed
(C) Closely bound
(D) Tightly fixed
The rest mass of an electron is
(A) 6.7 MeV
(B) 5.11 MeV
(C) 0.511 MeV
(D) 0.051 MeV
Potassium cathode in photocell emit electrons for a light
(A) Visible
(B) Infra-red
(C) Ultra violet
(D) X-rays
The rest mass energy of an electron positron pair is
(A) 0.51 Mev
(B) 1.02 Mev
(C) 1.2 Mev
(D) 1.00 Mev
If an electron of charge is accelerated through a potential difference V, it will acquire energy
(A) Ve
(B) VA
(C) %
(D) Vet
Charge on an electron was determined by
(A) Ampere
(B) Maxwell
(C) Milikan
(D) Neil Bohr
The reverse process of photo-electric effect is
(A) Compton effect
(B) X-rays production
(C) pair production
(D) pair annihilation
The physical quantity related to photon that does not change in Compton scattering is
(A) Energy
(B) Speed
(C) Frequency
(D) Wavelength
Which one is a photo conductor?
(A) Copper
(B) Selinium
(C) Mercury
(D) Aluminium
In photovoltaic cell, current is directly proportional to
(a) Wavelength of light
(b) Intensity of light
(c) Frequency of light
(d) Energy
For the computation of electric flux, the surface area should be
(A) Flat
(B) Curved
(C) Inclined
(D) Spherical
SI unit of electric flux is
(A) N — mC-2
(B) N — m2C-1
(C) N Cm-2
(D) N — C2m2
The S.I unit of magnetic flux is given by
(A) NmA-1
(B) NA-1m-1
(C) Nm2A-1
(D) Nrn-1A
The unit of magnetic flux is
(A) Curie
(B) Weber
(C) Newton
(D) Farad
Presence of dielectric always
(A) Increases the electrostatic force
(B) Reduces the electrostatic force
(C) Does not affect the electrostatic force
(D) Doubles the electrostatic force
The direction of induced current is always so as to oppose the change which causes the current is
(A) Faraday’s law
(B) Lenz’s law
(C) Ohm’s law
(D) Kirchoffs 1st rule
Whenever current is drawn from cell its terminal potential difference and e.m.f. becomes
(A) Different
(B) Same
(C) Zero
(D) Negative
Torque on a current carrying coil is given by
(A) ILB cos a
(B) ILB sin a
(C) IBA,cos a
(D) IBA sin a
Direct current cannot flow through
(A) Inductor
(B) Resistor
(C) Transistor
(D) Capacitor
The working principle of transformer is
(A) Self induction
(B) Faraday’s law
(C) Mutual induction
(D) Electromagnetic induction
The graphical representation of Ohm’s law is
(A) Hyperbola
(B) Ellipse
(C) Parabola
(D) Straight line
Joule hyper second is the unit of
(A) Energy
(B) Heat
(C) Plank’s constant
(D) Work
Glass and high carbon steel are example of
(A) Vductile substances
(B) Brittle substances
(C) Soft material
(D) Hard material
The division and germer experiment indicates
(A) Interference
(B) Polarization
(C) Electron diffraction
(D) Refraction
The division and germer experiment indicates
(A) Interference
(B) Polarization
(C) Electron diffraction
(D) Refraction
An avometer is also called
(A) An ammeter
(B) A voltmeter
(C) A multimeter
(D) An ohm-meter
Balmer series lies in
(A) Ultraviolet region
(B) Visible region
(C) Infra red region
(D) All of these
When a radioactive nucleus emits a 13 particle the proton and neutron ratio
(A) Remain the same
(B) Increases
(C) Decreases
(D) Equals
The resistivity of a conductor increase with
(A) Increase in its length
(B) Increase in its area
(C) Increase in its temperature
(D) Decrease in its length
Light emitting diodes (LED) are made from semi-conductors
(A) Silicon
(B) Germanium
(C) Carbon
(D) Gallium arsenide
Einstein presented special theory of relativity in
(A) 1850
(B) 1920
(C) 1905
(D) 1932
Einstein was awarded Nobel Prize in Physics in
(A) 1905
(B) 1911
(C) 1918
(D) 1921
The value of temperature coefficient of resistance of most thermistor
(A) Positive
(B) Negative
(C) Zero
(D) Infmity
A system which deals with quanitities or variables which have only two iscrete value or state called
(A) Digital system
(B) Automatic system
(C) Logic system
(D) None
Siemem is the unit of
(A) Resistance
(B) Conductance
(C) Resistivity
(D) Conductivity
Sensitivity of a galvanometer can be increased by
(A) Decreasing the value of torsional couple
(B) Decreasing number of turns
(C) Decreasing area of plane of coil
(D) Decreasing magnetic field
Magnetic potential energy stored in an inductor depends upon
(A) Under root of the value of current
(B) Cube root of the value of current
(C) Cube of the value of current
(D) Square of the value of current
The work is stored in an inductor as
(A) Kinetic energy
(B) Elastic potential energy
(C) Magnetic potential energy
(D) Gravitational potential energy
The central region of a transistor is called
(A) Base
(B) Emitter
(C) Collector
(D) Neutral
Transistors are made from plastics
(A) Metals
(B) Insulator
(C) Doped
(D) Semi conductor
The thickness of base in a transistor is of the order of
(A) 10-3m
(B) 10-9m
(C) 10-6m
(D) 10-6mm
The base in a transistor is of the order of
(A) 10-6m
(B) I 0-4m
(C) em
(D) 10-m
Base of the transistor is very thin of the order of
(A) 10-2 m4
(B) 10 m
(C) le m
(D) 104 m
A pair of quark and antiquark makes
(A) Meson
(B) Baryon
(C) Photon
(D) Proton
Two down and one up quarks make
(A) Proton
(B) Neutron
(C) Photon
(D) Positron
A proton consists of quarks which are
(A) Two up, one down
(B) One up, two down
(C) All up
(D) All down
The SI unit of stress is the same as that of
(A) omentum
(B) pressure
(C) force
(D) length
The SI unit of stress is the same as that of
(A) Momentum
(B) Pressure
(C) Force
(D) Length
The ratio of applied stress to volumetric strain is called
(A) Young’s modulus
(B) Shear modulus
(C) Bulk modulus
(D) Tensile modulus
When a stress changes the shape of a body, it is called
(A) Volumetric stress
(B) Shear stress
(C) Tensile stress
(D) Compressional stress
The maximum stress which a, body can bear is
(A) Ultimate tensile stress
(B) Permanent stress
(C) Plastic stress
(D) Yield stress
A Rheostat can operate as a
(A) Transformer
(B) amplifier
(C) oscillator
(D) potential divider
Fractional change in resistance per Kelvin rise in temperature is called
(A) Conductance
(B) Resistance
(C) Resistivity
(D) Temperature
The amount of energy released in the fusion of four hydrogen nuclei form an alpha particle is equal to
(A) 2 Mev
(B) 25 Mev
(C) 100 Mev
(D) 200 Mev
In black body radiation’s at low temperature a body emits radiations of
(A) Long wavelength
(B) Small wavelength
(C) Medium wavelength
(D) High energy
Which of is used to determine the interval resistance of a cell
(A) Ammetei
(B) Voltmeter
(C) Galvanometer
(D) Potentiometer
The substances with conductivities between 10-1° and 10-2o (c2 m) are called
(A) Super conductors
(B) Insulators
(C) Semi conductors
(D) Conductors
The substance having negative temperature co-efficient is
(A) Carbon
(B) Iron
(C) Tungsten
(D) Gold
Which one is not a ferromagnetic substance?
(A) Cobalt
(B) Copper
(C) Nickle
(D) Iron
Nm-2 is called
(A) Ohm
(B) Ampere
(C) Volt
(D) Pascal
The e/m of a neutron is
(A) Less than electron
(B) Greater than electron
(C) Zero
(D) The same as electron
The building blocks of protons of neutrons arc called
(A) VIons
(B) Electrons
(C) Positrons
(D) Quarks
Strong nuclear force acts on
(A) Meson only
(B) Pions only
(C) Photons only
(D) Hadrons only
If the medium between the charges is not free space then electrostatic force will
(A) Increase
(B) Decrease
(C) Remain same
(D) None of these
Electromotive force is closely related to
(A) Electrical field intensity
(B) Magnetic field intensity
(C) Potential difference
(D) Inductance
Lenz’s law is in accordance with the law of conservation of
(A) Momentum
(B) Charge
(C) Angular momentum
(D) Energy
The ability of a body to return to its original shape is called
(A) Strain
(B) Stress
(C) Elasticity
(D) Plasticity
Tolerance for silver band is
(A) ± 10%
(B) ± 15%
(C) ± 20%
(D) ± 25%
If the resistance of 500 Q have fourth band of silver colour then its upper maximum resistance will be
(A) 600 Q
(B) 550 0
(C) 450 Q
(D) 400 Q
Which of the following series lies in the ultraviolet region?
(A) Lyman series
(B) Balmer series
(C) Pfund series
(D) Bracket series
Which one of the following requires a material medium for their propagation?
(A) Heat waves
(B) X-rays
(C) Sound waves
(D) Ultraviolet rays
The torque on Cement Carrying Coil is
(A) T = NIAB cos a
(B) T = BIL sin a
(C) T = NIAB sin a
(D) T = BIL cos a
In 1905, the special theory of relativity was proposed by
(A) Maxwell
(B) de-Broglie
(C) Bohr
(D) Einstein
The anode in the CRO is
(A) Control no. of waves
(B) Control brightness of spot formed
(C) Accelerates and focus the beam
(D) At negative potential with respect to cathode
The brightness of the spot on CRO screen is controlled by
(A) Anode
(B) Cathode
(C) Grid
(D) Deflecting plates
An avometer can also be called as
(A) Digital ammeter
(B) Digital CRO
(C) Digital voltmeter
(D) Multi mate
A potential barrier of 0.7 volt exist across p-n junction made from
(A) Silicon
(B) Germanium
(C) Indium
(D) Gallium
When a small resistance is connected parallel to the galvanometer, the resulting is
(A) Voltmeter
(B) Wheatstone bridge
(C) Ammeter
(D) Potentiometer
One weber is equal to
(A) NA-1
(B) Nm-1 A
(C) NmA -1
(D) Nm-1A-1
When a P-N junction is reverse biased, the depletion region is
(A) Widened
(B) Narrowed
(C) Normal
(D) No change
Which light photon has the least momentum
(A) Red
(B) Blue
(C) Yellow
(D) Green
The momentum of the moving photon is
(A) Zero
(B) P
(C) P = —
(D) P = X —
A positron is an antiparticle of
(A) Proton
(B) Electron
(C) Neutron
(D) Photon
The physical quantity related to photon that does not change in Compton scattering is
(A) Energy
(B) Speed
(C) Frequency
(D) Wavelength
Which of the following have no charge?
(A) ot-rays
(B) p-rays
(C) y-rays
(D) Cathode rays
In Helium-Neon laser, discharge tube is filled with Neon gas
(A) 10%
(B) 15%
(C) 85%
(D) 90%
Choke consumes extremely small
(A) Current
(B) Charge
(C) Power
(D) Potential
The velocity of an oscillating charge as it moves to and fro along a wire is
(A) Changing
(B) Constant
(C) Infinite
(D) Zero
The charge on f3-particle is
(A) +e
(B) —e
(C) +2e
(D) None of these
A particle carrying a charge of 2e falls through potential difference of 3v. Energy acquired by it is
(A) 9.6 x 10-16J
(B) 9.6 x 10-29.1
(C) 9.6 x 10-15 J
(D) 9.6 x 10-19 J
Fluorescence is the property of
(A) High frequency particles
(B) Moderate frequency particles
(C) Low frequency particles
(D) Visible light
If a platinum wire is heated at 500° C, then it appears as
(A) White
(B) Yellow
(C) Orange red
(D) Dull red
Universal gate is the gate which can perform the function of
(A) Buffer gate
(B) Any logic gate
(C) Any basic gate
(D) Any exclusive gate
Grid in cathode ray oscilloscope controls
(A) Number of electrons
(B) Temperature of filament
(C) Frequency of electrons
(D) Energy of electrons
By using NAVSTAR speed of an object can now be determined to an accuracy of
(A) 20 cm/sec
(B) 760 cm/sec
(C) 50 cm/sec
(D) 2 cm/sec
Energy of each positron is given by
(A) 2 MeV
(B) 1.02 MeV
(C) 0.51 MeV
(D) 5 MeV
Binding energy for deuteron nucleus is given by
(A) 2.8 Mev
(B) 2.23 Mev
(C) 2.28 Mev
(D) 2.25 Mev
The amount of energy acquired or lost by an alpha particle as it moves through p.d. of 1 V is
(A) 3.2 x 10-19J
(B) 6.4 x 10-19J
(C) 1.6 x 10-19J
(D) Zero
Specific resistance of a material depends upon
(A) Length
(B) Area
(C) Temperature
(D) Both A & B
Resistivity at a given temperature depends upon
(A) Area of cross section
(B) Length
(C) Nature of material of conductor
(D) Both length and area
Cathode ray oscilloscope works by deflecting a beam of
(A) Neutrons
(B) Protons
(C) Electrons
(D) Positrons
A light emitting diode (LED) emits light only when
(A) Reverse biased
(B) Forward biased
(C) Unbiased
(D) None of these
Life time of meta stable state is
(A) le s
(B) 10-3s
(C) 10-8s
(D) 10-2s
Which one belongs to Lepton’s group
(A) Electron
(B) Muons
(C) Neutrinos
(D) All of these
Equation (1) = EX is applicable to a surface
(A) Spherical
(B) Cylindrical
(C) Conical
(D) Flat
Which of the following has the least hysteresis loop area
(A) Steel
(B) Wrought iron
(C) Soft iron
(D) Cobalt
The open loop gain of the amplifier is order of
(A) 102
(B) 108
(C) 105
(D) 1012
Mass of meson is
(A) Greater than proton
(B) Less than proton
(C) Equal to proton
(D) Equal to neutron
Which one is used to study the circulation of blood?
(A) Iodine-131
(B) Sodium-24
(C) Cobalt-60
(D) Strontium-90
Which one pair belongs to accepter impurity
(A) Arsenic, phosphorus
(B) Boron, gallium
(C) Antimony, indium
(D) Arsenic, antimony
Which one is pentavalent impurity?
(A) Boron
(B) Gallium
(C) Antimony
(D) Indium
Potential difference across two terminal of silicon diode at 300 k is
(A) 0.3 V
(B) 0.7 V
(C) 0.9 V
(D) 1.2 V
Commutator was invented in
(A) 1736
(B) 1834
(C) 1935
(D) 1885
Which one of the following is crystalline solid
(A) Zirconia
(B) Glassy solid
(C) Natural rubber
(D) Polystrene
The value of Wien’s constant is
(A) 2.9×10-3mK
(B) 2.9x103mK
(C) 5.67x 10-8mK
(D) 5.67×10-8wm-2K-4
The number of isotopes of caesium are
(A) 4
(B) 32
(C) 36
(D) 22
The product of resistance and capacitance is
(A) Velocity
(B) Force
(C) Acceleration
(D) Time
The peak value of A.0 source is 20 A, then its rms valtie will be
(A) 14.1 A
(B) 10 A
(C) 20 A
(D) 28.2 A
