In a center-tap full-wave rectifier load resistance is 4 K. The a.c. supply across the transformer turn ratio, N1/N2 = and diode and secondary winding resistances are neglected, then the d.c. load voltage and current would be respectively
286.2 V and 71.55 mV
273.6 V and 76.35 mV
293.6 V and 79.31 mV
263.8 V and 75.71 mV
Electrical energy generated at a power plant is delivered to distant places over a long transmission cables at very high alternating voltage of about 330,000 volts. The reason for this is that
At high voltages, energy is delivered much faster than at low voltages
There is less wastage of energy at high voltages
The high voltage prevents the theft of costly transmission cables
It is much easier to generate large amount of electrical energy at high voltages
If the length of a heater coil is reduced by 105 of its original length, then power consumed by the heater will
Increase over 10%
Decrease by 10%
Increase by 0.5%
Decrease by 0.5%
When an electric field acts on the electrons in a conductor, it does not produce a net acceleration. This happens because the electrons keep on colliding with the atoms that make up the conductor. Thus the electrons acquire a constant average
Velocity
Speed
Drift speed
Escape velocity
In laboratory, Wheatstone bridge is used for the measurement of
Inductance
Capacitance
Resistance
None of the above
In a Wheatstone bridge, which of the following expressions is correct at balanced condition? (where, R1 and R2 are ratio arms, R3 is the known variable resistance and R4 is the unknown resistance.)
R1/R2 = R3/R4
R1/R4 = R3/R2
R1/R4 = R2/R3
R1/R2 = R3/R4
What the increase in temperature, the resistivity of all metallic conductors
Increases
Decreases
Remains constant
Sometimes increases and sometimes decreases
With increasing temperature, the resistivity of a semi-conductor
Decreases very rapidly
Increases very rapidly
Remains at a constant value
Increases very slowly
Which of the following metals has the lowest resistivity at room temperature?
Silver
Copper
Aluminium
Gold
For a long straight wire carrying current, I, the value of B is _____for all point at the same distance from the long straight wire
Same
Different
10 wb/m2
None of the above