A 25eV electron has a speed of
1.2 x 106m/sec
2.3 x 106m/sec
3.5 x 106m/sec
4.4 x 106m/sec
A 5 ?F capacitor has a potential difference across its plates of 200 volts. The charge on the capacitor is
1.2.5 x 10-8 C
2.10-5 C
3.103 C
4.4 x 103 C
A capacitor is a perfect insulator for
1.direct current
2.alternating current
3.both for the direct and alternating current
4.none of above
A charge of 0.10C accelerated through a potential difference of 1000V acquires kinetic energy
1.200J
2.100J
3.1000J
4.100 eV
A dynamo converts
1.mechanical energy into electrical energy
2.electrical energy into mechanical energy
3.magnetic energy into mechanical energy
4.magnetic energy into electrical energy
A.C and D.C have the same
1.effect in charging a capacitor
2.effect in charging a battery
3.effect while passing through an inductance
4.heating effect through a resistance
A.C cannot be used for
1.producing heat
2.producing light
3.magnetizing and electroplating
4.all the above
An alternating current or voltage
1.fluctuates off and on
2.varies in magnitude alone
3.changes its direction again and again
4.changes its magnitude continuously and reverses its direction of flow after regularly recurring intervals.
capacitor is to have an energy content of 20J it must be placed across a potential difference of
1.4 volts
2.9 volts
3.2 volts
4.1 vol
cmf generated by A.C dynamo depends upon
1.number of turns in the coil
2.magnetic field strength
3.frequency of rotation
4.all of above
Current produced by moving the loop of wire across a magnetic field is called
1.A.C current
2.D.C current
3.induced current
4.mean square current
Electric field due to positive charged plate is E = ?/2??. If oppositely charged plate of same amount is placed parallel to it, then resultant field contains amount of energy
1.Q/?oA
2.Q/e
3.QV2
4.Q2/C
Electric flux due to a point charge +q is
1.1/4II?? . q/r
2.q/??
3.1/4II?? . q/r2
4.4II??
Electric intensity at infinite distance from the point charge is
1.zero
2.infinite
3.positive
4.negative
emf induced in a circuit according to Faradays law depends on the
1.maximum magnetic flux
2.rate of change of magnetic flux
3.change in magnetic flux
4.initial magnetic flux
Energy stored in a magnetic field is given by
1.LI2
2.L2I/2
3.LI2/2
4.IL2
Equipotential planes are
1.parallel to one another
2.non parallel to one another
3.intersecting
4.circular
Equivalent capacitance is greater than individual capacitances in
1.series combination
2.parallel combination
3.both series and parallel combinations
4.none of above
For electroplating we use
1.A D.C source
2.an A.C source
3.any source
4.all of the above
For what value of ? the electric flux has average value of those of extreme values ?
1.60?
2.45?
3.90?
4.0?
If a charged rod is brought closer to a gas filled balloon then
1.Radius decreases
2.Balloon bursts
3.Radius increase
4.Balloon squeezes
If an electrons is allowed to move along the field in a non uniform electric field then it will follow
1.Spiral path
2.Straight line
3.Curved path
4.Circular path
If metallic conductor is charged negatively then its weight
1.Remains same
2.First increases then decreases
3.Decreases then increases
4.Increases for a while
If mica sheet is placed between the plates of a capacitor the capacity
1.increases
2.decreases
3.increases then decreases
4.decreases then increases
If the coil is wound on an iron core the flux through it will
1.decrease
2.become zero
3.remain the same
4.increase
If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by
1.Vs/Vp = Np/Ns
2.Vs/Vp = Ns/Np
3.Vp/Vs = Ns/Np
4.Vp/Vs = Np/Ns
If two charges are increased by two times then force
1.Decreases 9 times
2.Increases 9 times
3.Increases 4 times
4.Decreases 4 times
In a charged capacitor the energy resides in
1.magnetic hield
2.electric field
3.nuclear field
4.gravitational field
In a non-uniform electric field a polar molecule will experience
1.Net torque
2.Net force
3.both series and parallel combinations
4.zero
Inductors acts as a short circuit for
1.AC
2.DC
3.Both (a) and (b)
4.none of these
N/C =
1.V/A
2.J/V
3.V/m
4.A/m
Photocopier and inject printer are dealt in
1.Electrostatics
2.Charges in motion
3.Capacitors
4.Electric fields
Potential difference is the work done in moving unit positive charge form one point to another
1.in the direction of electric intensity
2.against electric intensity
3.in any direction
4.in the direction of electric flux
Power loss in actual transformer is due to
1.Small output
2.Eddy currents and magnetic hysterias
3.Soft iron core
4.Back emf
Selenium becomes a conductor in light so it behaves like
1.Semiconductor
2.Photodiode
3.Light emitting diode
4.Capacitor
Self inductance of a coil depends upon
1.current flowing
2.number of turns per unit length
3.voltage produce
4.all
SI unit of permitivity of free space is
1.Nm2C2
2.N-1mC-2
3.NmC-1
4.N-1m-2C2
The number of electrons in one coulomb charge is equal to
1.6.2 x 1018
2.1.6 x 1019
3.6.2 x 1021
4.1.6 x 10-27
The only difference between construction of D.C generator and A.C generator is that of
1.carbon brushes
2.coil
3.commutator
4.magnetic field
The practical illustration of the phenomenon of mutual induction is
1.A.C generator
2.D.C dynamo
3.induction coil
4.transformer
The value of the capacitance depends upon the
1.voltage applied
2.thickness of the capacitor plates
3.geometry of the capacitor
4.dinsity of the capacitor plates
Three capacitors C1 C2 and C3 are connected in parallel as in the Fig. The equivalent capacitance will be
1.8?F
2.0.8?F
3.1?F
4.16?F
Two oppositely charged balls A and B attract third conducting ball C when placed near them turn by turn. Then ball C must be
1.positively charged
2.electrically neutral
3.negatively charged
4.positively and negatively charged
Value of ?r for various dielectrics is always
1.less than unity
2.equal to unit
3.larger than unit
4.no hard and fast rule
Weber is the unit of
1.Magnetic field intensity
2.magnetic induction
3.magnetic flux
4.self-inductance
Which of the following uses electric energy and does not convert it into any other form?
1.transformer
2.motor
3.D.C generator
4.A.C generator
Which of the following works on torque on the current carrying conductor placed in magnetic field.
1.galvanometer
2.ammeter
3.voltmeter
4.all of the above
Which one of the following can be taken as the measure of electric intensity ?
1.F/A
2.?/A
3.???/A
4.q/??A
Which one of the following functions like a motor?
1.galvanometer
2.ammeter
3.voltmeter
4.all of above
Work done in moving a point charge from one point to another point of equipotential surface is
1.?W = 1?V
2.?W = F?r
3.zero
4.W = 1/4????V