Que- A sensitive galvanometer gives full-scale deflection with 100 mV. If the resistance of the galvanometer is 50 Ohm the maximum current that can flow through safely is
a. 2.0 mA
b. 20 mA
c. 200 mA
d. 0.2 mA
Answer- 2.0 mA
Que- An ammeter measures the total current flowing through a circuit when it is connected
a. in series with the circuit
b. in parallel with circuit
c. in series with any of the parallel resistances in the circuit
d. in parallel with any of the series resistances in the circuit
Answer- in series with the circuit
Que- Coil of a galvanometer is suspended in a radial magnetic field so that the deflecting torque on the coil is always
a. BINA cosa
b. BINA sina
c. BINA tana
d. BINA
Answer- BINA
Que- A galvanometer basically is an instrument used to
a. detect current in a circuit
b. measure current flowing through a circuit
c. measure voltage across a circuit
d. measure potential difference between two points in a circuit
Answer- detect current in a circuit
Que- The effective way to increase the sensitivity of a moving coil galvanometer is to
a. use a very long and fine suspension
b. use a coil of very large area
c. use a coil with very large number of turns
d. use a very strong magnetic field
Answer- use a very strong magnetic field
Que- A wheat stone bridge is said to be balanced when
a. maximum current flows through the galvanometer branch
b. minimum current flows through the galvanometer branch
c. potential difference across galvanometer branch is maximum
d. potential difference across galvanometer branch is zero
Answer- potential difference across galvanometer branch is zero
Que- When an electron moving with a uniform speed in a vacuum enters a magnetic field in a direction perpendicular to the field the subsequent path of the electron is
a. a straight line parallel to the field
b. a parabola in a plane perpendicular to the field
c. a circle in a plane perpendicular to the field
d. a straight line along its initial direction
Answer- a circle in a plane perpendicular to the field
Que- A particle of mass m charge q and speed V enters a uniform magnetic radius r. The radius r of the circle is
a. independent mass m
b. directly proportional to m
c. directly proportional to q
d. directly proportional to B
Answer- directly proportional to m
Que- Galvanometer is a very sensitive device with
a. very low damping
b. very high damping
c. no damping at all
d. radial field disintegration
Answer- very low damping
Que- Which one of the following methods would be able to increase the sensitivity of a moving coil galvanometer ?
a. connect a shunt across the coil
b. use a coil of smaller cross sectional area
c. use a coil having less number of turns
d. use spiral springs whose force constant is small
Answer- use spiral springs whose force constant is small
Que- Heating a magnet will
a. weaken it
b. strengthen it
c. reverse its polarity
d. demagnetize it completely
Answer- weaken it
Que- If a current carrying solenoid is suspended freely it will
a. be rotating
b. come to rest in N-S direction
c. vibrating like galvanometer needle
d. comes to rest after rotation
Answer- come to rest in N-S direction
Que- The practical illustration of the phenomenon of mutual induction is
a. A . C generator
b. D . C dynamo
c. induction coil
d. transformer
Answer- transformer
Que- Weber is the unit of
a. Magnetic field intensity
b. magnetic induction
c. magnetic flux
d. self-inductance
Answer- magnetic flux
Que- Current produced by moving the loop of wire across a magnetic field is called
a. A . C current
b. D . C current
c. induced current
d. mean square current
Answer- induced current
Que- emf induced in a circuit according to Faradays law depends on the
a. maximum magnetic flux
b. rate of change of magnetic flux
c. change in magnetic flux
d. initial magnetic flux
Answer- rate of change of magnetic flux
Que- cmf generated by A . C dynamo depends upon
a. number of turns in the coil
b. magnetic field strength
c. frequency of rotation
d. all of above
Answer- all of above
Que- An alternating current or voltage
a. fluctuates off and on
b. varies in magnitude alone
c. changes its direction again and again
d. changes its magnitude continuously and reverses its direction of flow after regularly recurring intervals.
Answer- changes its magnitude continuously and reverses its direction of flow after regularly recurring intervals.
Que- A dynamo converts
a. mechanical energy into electrical energy
b. electrical energy into mechanical energy
c. magnetic energy into mechanical energy
d. magnetic energy into electrical energy
Answer- mechanical energy into electrical energy
Que- Which one of the following functions like a motor?
a. galvanometer
b. ammeter
c. voltmeter
d. all of above
Answer- all of above
Que- A . C cannot be used for
a. producing heat
b. producing light
c. magnetizing and electroplating
d. all the above
Answer- magnetizing and electroplating
Que- Which of the following works on torque on the current carrying conductor placed in magnetic field.
a. galvanometer
b. ammeter
c. voltmeter
d. all of the above
Answer- all of the above
Que- Self inductance of a coil depends upon
a. current flowing
b. number of turns per unit length
c. voltage produce
d. all
Answer- all
Que- If the coil is wound on an iron core the flux through it will
a. decrease
b. become zero
c. remain the same
d. increase
Answer- increase
Que- Energy stored in a magnetic field is given by
a. LI2
b. L2I/2
c. LI2/2
d. IL2
Answer- LI2/2
Que- Inductors acts as a short circuit for
a. AC
b. DC
c. Both (a) and (b)
d. none of these
Answer- DC
Que- For electroplating we use
a. A D . C source
b. an A . C source
c. any source
d. all of the above
Answer- A D . C source
Que- Which of the following uses electric energy and does not convert it into any other form?
a. transformer
b. motor
c. D . C generator
d. A . C generator
Answer- transformer
Que- The only difference between construction of D . C generator and A . C generator is that of
a. carbon brushes
b. coil
c. commutator
d. magnetic field
Answer- commutator
Que- A . C and D . C have the same
a. effect in charging a capacitor
b. effect in charging a battery
c. effect while passing through an inductance
d. heating effect through a resistance
Answer- heating effect through a resistance
Que- If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by
a. Vs/Vp = Np/Ns
b. Vs/Vp = Ns/Np
c. Vp/Vs = Ns/Np
d. Vp/Vs = Np/Ns
Answer- Vs/Vp = Ns/Np
Que- Power loss in actual transformer is due to
a. Small output
b. Eddy currents and magnetic hysterias
c. Soft iron core
d. Back emf
Answer- Eddy currents and magnetic hysterias
Que- A metal rod of 25 cm length is moving at a speed of 0.5/sec in direction perpendicular to 0.25T magnetic field. Emf produced in the rod is
a. 0 volt
b. 3.125 volt
c. 31.25 volt
d. 0.03125 volt
Answer- 0.03125 volt
Que- The emf induced in a coil by a changing magnetic flux may have unit as
a. ms-1A
b. ms-2A-1
c. kgms2A-1
d. kgm2s-1A-1
Answer- kgm2s-1A-1
Que- The emf induced in a conductor of unit length moving with unit velocity at right angles to a magnetic field is equal to
a. Magnetic flux density
b. Torque
c. Mutual induction
d. Motional emf
Answer- Magnetic flux density
Que- The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core
a. Decreases the resistance of the solenoid
b. Reduces the effect of eddy current
c. Improves the flux linkage between the turns of the coil
d. Increases the mutual inductance between the solenoid and the core
Answer- Improves the flux linkage between the turns of the coil
Que- A small coil lies inside a large coil. The two coils are horizontal concentric and carry currents in opposite directions. The large coil will experience
a. A torque about horizontal axis
b. A torque about vertical axis
c. An upward force along the axis
d. No resultant force
Answer- No resultant force
Que- An aeroplane of wingspan 10m flies from the equator towards the North Pole. The wings are perpendicular to the vertical component of the earths magnetic field (B = 4x10-5T). At maximum speed an emf of 96mV is induced across the wing tips. The maximum speed of the aeroplane is
a. 150msec-1
b. 384msec-1
c. 38.4msec-1
d. 200msec-1
Answer- 384msec-1
Que- A . C can not be used for
a. producing heat
b. producing light
c. Magnetizing iron
d. Producing magnetic field
Answer- Magnetizing iron
Que- Non inductive resistances are used in decreasing
a. Mutual inductance
b. Self inductance
c. Magnetic fields
d. Heating effect
Answer- Self inductance
Que- Magnetic compass needle will be deflecting if it is kept near
a. Static charge
b. Soft iron
c. Semi-conductor
d. Accelerating charge
Answer- Accelerating charge
Que- Long distance transmission is easy for
a. D . C voltage
b. A . C voltage
c. Half A . C voltage
d. Half D . C voltage
Answer- A . C voltage
Que- Which one of the following devices does not function like an electric motor?
a. Galvanometer
b. Ammeter
c. Voltmeter
d. Transformer
Answer- Transformer
Que- The out put voltage of a transformer is 3 times the input voltage then turns ratio will be
a. 3-Jan
b. 3
c. 1
d. 6
Answer- 3
Que- For long distance transmission the transformer used is
a. Step down
b. Input voltage and output voltage remain same
c. Step up
d. Amplifier is used
Answer- Step up
Que- An electric current induced within the body of a conductor when that conductor either moves through a non uniform magnetic field or in a region where there is a change in magnetic flux is called
a. Induced current
b. Eddy current
c. Back emf
d. None of the above
Answer- Eddy current
Que- Lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied is known as magnetic
a. Retaintivity
b. Permeability
c. Flux
d. Hysteresis
Answer- Hysteresis
Que- Transformer works on the principle of
a. Lenzs law
b. Faradays law
c. Mutual induction
d. Law of conservation of power
Answer- Mutual induction
Que- When the motor is at its maximum speed then back emf will be
a. Maximum
b. Zero
c. Intermediate values
d. No back emf
Answer- Maximum
Que- An alternating current or voltage
a. fluctuates off and on
b. varies in magnitude alone
c. changes its direction again and again
d. changes its magnitude harmonically and reverses its direction of flow after regularly recurring intervals.
Answer- changes its direction again and again
Que- A changing magnetic flux produces around itself an induced
a. Magnetic field
b. Electric field
c. Electromagnetic force
d. Artificial gravitational field
Answer- Electromagnetic force
Que- Electromagnetic waves travel in free space with the speed of
a. ?-rays
b. Positive rays
c. Cathode rays
d. More than sound waves
Answer- ?-rays
Que- The direction of propagation of an electromagnetic waves is
a. Perpendicular to electric field
b. Perpendicular to both electric and magnetic field
c. Perpendicular to magnetic field
d. Parallel to electric and magnetic field
Answer- Perpendicular to both electric and magnetic field
Que- An electromagnetic wave consists of
a. Electric and magnetic fields moving parallel to each other
b. Magnetic field moving with velocity of light in space
c. Electric field moving with velocity of light
d. Electric and magnetic fields moving perpendicular to each other
Answer- Electric and magnetic fields moving perpendicular to each other
Que- Electromagnetic waves transport
a. Energy
b. Momentum
c. Mass
d. Heat
Answer- Energy
Que- Waves emitted from the antenna are
a. Sound waves
b. Electromagnetic waves
c. Radio waves
d. Modulated waves
Answer- Electromagnetic waves
Que- Electromagnetic waves emitted from antenna are
a. Stationary
b. Longitudinal
c. Transverse
d. All the above
Answer- Transverse
Que- If capacitance of L-C circuit is made four times then frequency of the circuit becomes
a. Twice
b. One half
c. Four times
d. None
Answer- One half
Que- A capacitor of capacitance 30 Degree F is charged by a constant current of 10mAIf initially the capacitor was uncharged what is the time taken for the potential difference across the capacitor to reach 300V?
a. 0.9sec
b. 15 sec
c. 1.5x105sec
d. 0.9x102sec
Answer- 0.9sec
Que- The value of the steady current which when flowing through the same resistor produces heat at the same rate as the mean rate of heat produced by the alternating current is
a. Average current
b. Sinusoidal current
c. r.m.s current
d. Net current
Answer- r.m.s current
Que- To find the r.m.s value of an alternating current mathematically we need to have
a. Mean value of I2
b. Square root of mean value of I2
c. Square root of I2
d. Square of 1/2
Answer- Square root of mean value of I2
Que- An alternating current of r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing 10 ohm resistor. The peak current is then
a. 20A
b. 20.66A
c. 6.66A
d. 5.66A
Answer- 5.66A
Que- pure resistor circuit the voltage and current are
a. Lagging each other
b. They are at 90 Degree phase difference
c. They have zero phase difference
d. No phase difference
Answer- They have zero phase difference
Que- If a glass plate is inserted in between the plate of a capacitor in series with a lighted bulb the brightness of the bulb
a. Remains same
b. Brightness increases
c. Brightness decreases
d. No light
Answer- Brightness increases
Que- A pure variable resistor is connected in series with a pure capacitor of fixed capacitance. The impedance of the circuit
a. Remains
b. Becomes infinite
c. Becomes zero
d. Increases
Answer- Increases
Que- Ammeter connected in an AC circuit measures
a. Exact value of current
b. rms value of current
c. Net value of current
d. Peak value of current
Answer- rms value of current
Que- When a pure inductor of inductance L and a pure capacitor of capacitance C are connected in parallel to a sinusoidal potential difference V the potential difference across both L & C will be
a. Same
b. Different
c. At L will be more than at C
d. At L will be less than at C
Answer- Same
Que- What is the self inductance of a coil in which an induced emf of 2V is set up when the current changes at the rate of 4 As-1?
a. 0.5 mH
b. 0.5H
c. 2.0H
d. 8.0H
Answer- 0.5H
Que- A choke is used as a resistance in
a. DC circuit
b. AC circuits
c. Both AC and DC circuit
d. Full wave rectifier circuit
Answer- AC circuits
Que- Choose the correct statement. In the case of AC circuit ohms law holds for
a. Peak values of voltage and current
b. Effective values of voltage and current
c. Instantaneous values of voltage and current
d. All of the above
Answer- All of the above
Que- The phase angle between the voltage and the current in an AC circuit consisting of a resistance is
a. Zero
b. 45 Degree
c. 90 Degree
d. 180 Degree
Answer- Zero
Que- In an LCR series circuit, if V is the effective value of the applied voltage VR is the voltage across R VL is the effective voltage across L & Vc is the effective voltage across C then
a. V = VR+VL+VC
b. V2 = VR2+VL2+VC2
c. V2 = VR2+(VL-VC)2
d. V2 = VL2+(VR-VC)2
Answer- V2 = VR2+(VL-VC)2
Que- Two identical coaxial circular loops carry equal currents in the same direction. If the loops approach each other the current in
a. Each increases
b. Each decreases
c. Each remains the same
d. One increases whereas that in the other decreases
Answer- Each decreases
Que- An inductor may store energy in
a. its electric field
b. its coils
c. its magnetic field
d. both electric and magnetic fields
Answer- its magnetic field
Que- Which of the following substances posses the highest elasticity?
a. Rubber
b. Steel
c. Glass
d. Copper
Answer- Steel
Que- What is the SI unit of modulus of elasticity of substance?
a. Nm-2
b. Jm-2
c. Nm-1
d. Being a number it has no unit.
Answer- Nm-2
Que- Which one of the following physical quantities does not have the dimensions of force per unit area?
a. Stress
b. Strain
c. Youngs modulus
d. Pressure
Answer- Strain
Que- A rubber cord of cross-sectional area 2cm2 has a length of 1m. When a tensile force of 10N is applied the length of the cord increases by 1cm. What is the youngs modulus of rubber?
a. 2x108 Nm-2
b. 5x106 Nm-2
c. 0.5x10-6 Nm-2
d. 0.2x10-6Nm-2
Answer- 5x106 Nm-2
Que- A wire suspended vertically from one end is stretched by attaching a weight of 20N to the lower end. The weight stretches the wire by 1mm. How much energy is gained by the wire?
a. 0.01J
b. 0.02J
c. 0.04J
d. 1.0J
Answer- 0.01J
Que- A certain stress applied to an elastic material produces a certain strain in it. If the elastic limit is not exceeded the energy gained per unit volume of the material is given by
a. Stress/strain
b. (stress/strain)
c. Stress x strain
d. (Stress / strain)
Answer- (Stress / strain)
Que- A uniform steel wire of length 4m and area of cross-section 3x10-6m2 is extended by 1mm by the application of a force. If the youngs modulus of steel is 2x1011 Nm-2 the energy stored in the wire is
a. 0.025J
b. 0.50J
c. 0.75J
d. 0.100J
Answer- 0.75J
Que- The ration stress to strain in youngs modulus of the material then tension is
a. Directly proportional to extension.
b. Directly proportional to strain.
c. Directly proportional to square of amplitude.
d. Inversely proportional to extension.
Answer- Directly proportional to extension.
Que- Materials that undergo plastic deformation before breaking are called
a. Brittle
b. Ductile
c. Amorphous
d. Polymers
Answer- Ductile
Que- A wire is stretched by a force F which causes an extension
a. The energy stored in the wire is
b. The extension of the wire is proportional to the force applied
c. The weight of the wire is negligible
d. The wire is not stretched beyond its elastic limit
Answer- The energy stored in the wire is
Que- A wire obeys Hooks law is of length 11 when it is in equilibrium under a tension F
a. Its length becomes 12 when the tension is increased to F
b. The energy stored in the wire during this process is
c. (F1+F2) (121+122)
d. (F1+F2) (122-112)
Answer- (F1+F2) (12-11)
Que- Formation of large molecule by joining small molecules is
a. Fusion
b. Polymerization
c. Crystallization
d. Subtraction
Answer- Polymerization
Que- Any alteration produced in shapes length or volume when a body is subjected to some external force is called
a. Stiffness
b. Toughness
c. Extension
d. Deformation
Answer- Deformation
Que- The energy band occupied by the valence electrons is called
a. Energy state
b. Valence band
c. ve energy state
d. conduction band
Answer- Valence band
Que- The curie temperature is that at which
a. Semi-conductor becomes conductors
b. Ferromagnetic becomes paramagnetic
c. Paramagnetic becomes diamagnetic
d. Metals become super conductor
Answer- Ferromagnetic becomes paramagnetic
Que- A ferromagnet will become fully magnetized at
a. High voltage A . C
b. Low voltage A . C
c. Alternating current at its peak value
d. D . C current at peak value
Answer- Alternating current at its peak value
Que- Coercive force is the force which opposes
a. Demagnetization
b. Breakage
c. Extension
d. Surface cracking
Answer- Demagnetization
Que- Materials in which valence electrons are tightly bound to their atoms at low temperature are called
a. Semi conductor
b. Super conductors
c. Insulators
d. Conductor
Answer- Insulators
Que- The bulk properties of materials such as their mode of fracture can be related to their
a. Polymerization
b. Cleavage
c. Microstructure
d. Dislocation
Answer- Microstructure
Que- The angular position of cells remains the same for a sample of a crystal. This property is called
a. Isotropy
b. Cleavage
c. Homogeneity
d. The external symmetry of form
Answer- The external symmetry of form
Que- The breaking of crystals along definite direction is called
a. Cleavage
b. Symmetry
c. Isotropy
d. Homogeneity
Answer- Cleavage
Que- If the density of atoms remain same along any direction in a crystal is called
a. Symmetry
b. Homogeneity
c. Isotropy
d. Cleavage
Answer- Homogeneity
Que- In simple cube one atom or molecule lies at its
a. Force corners
b. Nine corners
c. Eight corners
d. Six corners
Answer- Eight corners
Que- The band theory of solids explains satisfactorily the nature of
a. Electrical insulators alone
b. Electrical conductors alone
c. Electrical semi conductors alone
d. All of the above
Answer- All of the above
Que- A vacant or partially filled band is called
a. Conduction band
b. Valence band
c. Forbidden band
d. Empty band
Answer- Conduction band
Que- A completely filled band is called
a. Conduction band
b. Valence band
c. Forbidden band
d. Core band
Answer- Core band