A 100?F capacitor with 12V source in series having frequency 50Hz will offer a capacitive reactance of about
1.32?
2.62?
3.50?
4.100?
A capacitor of capacitance 30?F is charged by a constant current of 10mA. If initially the capacitor was uncharged what is the time taken for the potential difference across the capacitor to reach 300V?
1.0.9sec
2.15 sec
3.1.5x105sec
4.0.9x102sec
A changing magnetic flux produces around itself an induced
1.Magnetic field
2.Electric field
3.Electromagnetic force
4.Artificial gravitational field
A fuse is placed in series with the cireuit to protect against
1.high power
2.high voltage
3.high current
4.over heating
A neon flashlight cell with an emf of 1.5V gives a current of 15A when connected directly to an ammeter of resistance 0.04?. Internal resistance of the cell is
1.0.0004?
2.0.06?
3.0.10?
4.0.13?
A pure variable resistor is connected in series with a pure capacitor of fixed capacitance. The impedance of the circuit
1.Remains
2.Becomes infinite
3.Becomes zero
4.Increases
A wire of resistance R is coiled inductively so that its inductance is L. The impedance of the coil at a frequency of f is
1.(R+2?fL)
2.R+1/2?fL
3.(R2+f2L2)
4.(R2+4?2f2L2)
All electrical appliances are connected in parallel to each other between the main line and neutral wire to get
1.same current
2.same current and potential difference
3.different current but same potential difference
4.different current and potential differences
Ammeter connected in an AC circuit measures
1.Exact value of current
2.rms value of current
3.Net value of current
4.Peak value of current
An alternating current is represented by the equation I = I?sin?t which of the following equation represents an alternating current of frequency and amplitude twice that of the above current?
1.I = 2I?Sin(?t/2)
2.I = 2I?Sin(2?t)
3.I = 2ISin?t
4.I = I?sin(2?t)
An alternating current of r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing 10? resistor. The peak current is then
1.20A
2.20.66A
3.6.66A
4.5.66A
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 harmonically and reverses its direction of flow after regularly recurring intervals.
An electric iron is marked 20 volts 500W. The units consumed by it in using if for 24 hours will be
1.12
2.24
3.5
4.1100
An electromagnetic wave consists of
1.Electric and magnetic fields moving parallel to each other
2.Magnetic field moving with velocity of light in space
3.Electric field moving with velocity of light
4.Electric and magnetic fields moving perpendicular to each other
An immersion heater of 400 watts kept on for 5 hours will consume electrical power of
1.2KWh
2.20KWh
3.6KWh
4.12KWh
Circuit which gives continuously varying potential is called
1.complex network
2.wheat stone bridge
3.potential divider
4.all of above
Electrical energy is converted to heat at the rate of
1.IRt
2.I2R
3.I2Rt
4.VIt
Electrical energy is measured in
1.watt
2.horse power
3.kilo watt
4.kilowatt hour
Electromagnetic waves emitted from antenna are
1.Stationary
2.Longitudinal
3.Transverse
4.All the above
Electromagnetic waves transport
1.Energy
2.Momentum
3.Mass
4.Heat
Electromagnetic waves travel in free space with the speed of
1.?-rays
2.Positive rays
3.Cathode rays
4.More than sound waves
If 1 ampere current flows through 2m long conductor the charge flow through it in 1 hour will be
1.3600C
2.7200C
3.1C
4.2C
If a glass plate is inserted in between the plate of a capacitor in series with a lighted bulb the brightness of the bulb
1.Remains same
2.Brightness increases
3.Brightness decreases
4.No light
If capacitance of L-C circuit is made four times then frequency of the circuit become
1.Twice
2.One half
3.Four times
4.None
In capacitive circuit the current
1.Lags behind voltage by ?/2
2.Is in phase with voltage
3.Opposite in phase of voltage by ?
4.Leads forward the voltage by ?/2
In liquids and gases the current is due to the motion
1.negative charges
2.positive charges
3.both negative and positive charges
4.neutral particles
In the following figure, the terminal potential is
1.zero
2.2V
3.12V
4.36V
Internal resistance is the resistance offered by
1.source of e m f
2.conductor
3.resistor
4.capacitor
pure resistor circuit the voltage and current are
1.Lagging each other
2.They are at 90? phase difference
3.They have zero phase difference
4.No phase difference
Reciprocal of resistivity is called
1.resistance
2.inductance
3.conductivity
4.flexibility
Resistance between points A and B in the circuit shown in figure is
1.4?
2.6?
3.10?
4.8?
Resistance of a super conductor is
1.finite
2.infinite
3.zero
4.changes with every conductor
Resistance of a wire on increasing its temperature will
1.increase with rise in temperature
2.decrease with rise in temperature
3.will remain same
4.depends upon altitude of experimentation
Resistance of an ideal insulator is
1.infinite
2.zero
3.finite
4.depends upon nature
Specific resistance of a wire
1.will depend on its length
2.will depend on its radius
3.will depend on the type of material of the wire
4.will depend on none of the above
Terminal potential difference of a battery is greater than its emf when
1.the internal resistance of battery is infinite
2.the internal resistance of battery is zero
3.the battery is charged
4.the battery is discharged
The current in the circuit shown in figure - What will be the current in the circuit?
1.1/45A
2.1/10A
3.1/5A
4.5A
The direction of propagation of an electromagnetic waves is
1.Perpendicular to electric field
2.Perpendicular to both electric and magnetic field
3.Perpendicular to magnetic field
4.Parallel to electric and magnetic field
The graphical representation of Ohms law is
1.hyperbola
2.ellipse
3.parabola
4.straight line
The resistance of a conductor at absolute zero (OK) is
1.zero almost
2.infinite almost
3.no prediction at all
4.may increase or decrease
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
1.Average current
2.Sinusoidal current
3.r.m.s current
4.Net current
There are three bulbs of 60W 100W and 200W which bulb has thickest filament
1.100W
2.200W
3.60W
4.all
Three bulbs are rating 40W 60W and 100W designed to work on 220V mains. Which bulb will burn most brightly if they are connected in series across 220 V mains?
1.40 W bulb
2.60 W blub
3.100 W blub
4.all will burn equally brightly
To find the r.m.s value of an alternating current mathematically we need to have
1.Mean value of I2
2.Square root of mean value of I2
3.Square root of I2
4.Square of 1/2
Waves emitted from the antenna are
1.Sound waves
2.Electromagnetic waves
3.Radio waves
4.Modulated waves
When 2? 4? and 6? resistor are connected in parallel their resultant equivalent resistance will be
1.12?
2.11/12?
3.12/11?
4.data is insufficient
Which one is the best material for making connecting wires?
1.iron
2.tungsten
3.silver
4.copper
Which one of the following bulbs has the least resistance?
1.100 watt
2.200 watt
3.300 watt
4.60 watt
Which one of the following materials is useful for making bulb filaments?
1.constantan
2.nichrome
3.copper
4.tungsten
Why should a resistance be introduced in a circuit in series deliberately?
1.to increase current
2.to decrease current
3.to control current
4.just to give a good look to circuit