If induction motor is direct switched-on then it will develop
Two bulbs 100W, 250 V and 200 W, 250 V are connected in series across a 500V line then-
Which of the following characteristics of electrons determines the current in a conductor?
The current in the given circuit with a dependent voltage source is
Three current i1, i2 and i3 are approaching a mode. If i1=10 sin (400 t + 60º) A and i2 = 10 sin (400 t +60º) A, then i3 is
The figure shows a network in which the diode is an ideal one
The terminal V-I characteristics of the network is given by
In a network made up of linear resistors and ideal voltage sources, values of all resistors are doubled. Then the voltage across each resistor is
Even on changing the values of linear resistors, the voltage remains constant in case of ideal voltage source.
Consitor the following circuit
What is the value of the current I in the above circuit?
For the circuit shown in the given figure the current through L and the voltage across C2 are respectively
A unit impulse voltage is applied at t=0 to the RL circuit shown below while i (0-)= 1A. What isthe expression for i (t)?
It the circuit shown in the figure given below, the switch is opened at t = 0 after having been closed for a long time. What is the current through 50W resistor?
For the circuit shown in the given figure the current I is given by
The value of V in the circuit shown in the given figure is
where I = 3A
Capacitors charge and discharge in __________ manner.
Consider the circuit given below, what is the power delivered by the 24 V source?
A straight conductor of circular x-section carries a current.which one of the following statement is true in this regard?
A cast steel electromagnet has an air gap length of 0.3 cm. Find the ampere turns for the air gap to produce a flux density of 0.7 wb/m2 in the air gap
A magnetic circuit requires 800 AT to produce a certain quantity of flux in the magnetic circuit. If the excitation coil has 100 turns and 5W resistance, the voltage to be applied in the excitingcoil is
The principle of dynamically induced emf is utilised in a
Lower the self inductance of the coil
Two coupled coils connected in series have an equivalent inductance of 16 mH or 8 mH depending on its inter connection. Then the mutual inductance M between the coil is
The overall inductance of two coils connected in series, with mutual inductance aiding self inductance is L1, with mutual inductance opposing self inductance the overall inductance is L2 . The mutual inductance M is given by
Power factor is highest in case of
The purpose of providing choke in a tube light is
Blinking of Fluorescent tube may be on account of
The current drawn by a 220 V dc motor of armature resistance 0.5W and back emf 200V is
A dc shunt generator when driven without connecting field winding shows an open circuit terminal voltage of 12V. When field winding is connected and excited the terminal voltage drop to zero because
A dc series motor is accidently connected to single phase a.c. suply. The torque produced will be
At 1200 rpm, the induced emf of a dc machine is 200 V. For an armature current of 15 A the electromagnetic torque produced would be
Determine the flux per pole for 6 pole dc machine having 240 wave connected conductors, which generates an open circuit voltage of 500 volt.Which is running at 1000 rpm
The armature resistance of a 6 pole lap wound d.c. machine is 0.05W. If the armature is rewound as a wave winding. What is the armature resistance.
A 200/100V, 50Hz transformer is to be excited at 40 Hz. from the 100 V side for the exciting current to remain same the applied voltage should be
Iron losses in a D.C machines are independent of variation in
As a result of armature reaction, the reduction in the total mutual air gap flux in a DC generator is approximately
Which motor has the poorest speed control?
Which of the following application requires high starting torque?
For constant torque drive which speed control method is preferred?
A 100 VA, 120/12V transformer is to be connected so as to form a step-up transformer. A primary voltage of 120V is applied to the transformer. What is the secondary voltage of the transformer?
The synchronizing reactance of a 500V 50 KVA alternator having an effective resistance of 0.2W, if an excitation current of 10 A produces 200A armature current on short circuit and an emf of 450 volts on open circuit is
When the rotor speed, in a synchronous machine becomes more than the synchronous speed during hunting, the damper boars develop
The starting current of a 3–f induction motor is 5 times the rated current, while the rated slip is 4%. The ratio of starting torque to full load torque is
Squired cage bars place in the rotor pole faces of an alternator help reducing hunting
A 3-f synchronous motor has
Which of the following device can be used as a phase advancer?
Capacitor in a single phase induction motor is used for
The repulsion start induction motor has the advantage of
Single phase induction motor built with a variable air gap and without dc excitation is called____ motor
A hysteresis motor
Which of the following motors are used in largest number?
A Buchholz relay is used for
Which type of connection is employed a for current transformers for the protection of stardelta connected 3–f transformer?
Which circuit breaker is preferred to be installed in extra high voltage AC system?
A generating station has a maximum demand of 30 MW, a load factor of 60% and a plant capacity factor of 50%. The reserve capacity of the plant is
The rating of fuse wire is always expressed in
Transmission of power by ac cables is impossible beyond.
Earth wire should be
Low power factor is usually not due to
A power station has a maximum demand of 15000 KW. The annual load factor is 50% and plant capacity factor is 40%. What is the reserve capacity of the plant?
If all the sequence voltages at the fault point in a power system are equal, then the fault is a
A 10 kVA, 400 V/200V single phase transformer with 10% impedance, draws a steady shor tcircuit current of
The breakdown voltage of a cable depends upon
As per electricity regulations in India the maximum permissible voltage change at consumer premises should be
On what basis is the insulation level of a 400 KV, EHV overhead transmission line decided?
Series capacitors can be used in distribution lines
Merz-price protection is employed for protection of
Impulse ratios of insulator and lightening arrestor should be
In a thyrite lightning arrester the resistance
A typical active load is
For quick speed reversal the motor preferred is
Ward-leonard controlled dc drives are usually used for _____ duty excavators
The underground system cannot be operated above
An instrument which detects electric current is known as
Which of the following transducer is classified as an active transducer?
A first order instrument is characterized by
Which of the following instrument will be used to measure a small current of very high frequency?
Which one of the following passive components has the most precise and accurate standard?
An ac voltmeter using full wave rectification and having sinusoidal input has an ac sensitivity equal to
A spring controlled moving iron voltmeter draws a current of 1mA for full scale value of 100V. If it draws a current of 0.5 mA, the meter reading is
By mistake, an ammeter is used as a voltmeter. In all probabilities, it will
To minimise voltmeter loading
A standard resistance is made 'Bifilar' type to eliminate
Maxwell's inductance capacitance bridge is used for measurement of inductance of
Electrostatic type instruments are mainly used for measurement of:
In a two wattmeter method of measuring 3-f power, the wattmeter indicate equal and opposite readings. When load power factor is
In eddy currents damping system, the disc employed should be of
If the instrument has square law response, it can be used for the measurement of
Error due to hysteresis is predominant in
To measure current in the MHz range we use instrument of
The shunt type ohmmeter is not suitable for high resistance measurement because
Ebers - model of a transistor represents two diodes
In an N-P-N transistor, the leakage current is due to
The action of JFET in its equivalent circuit can best be represented as a
In JFET drain current is maximum when VGS is
The diffusion current is proportional to
For highly doped diode
The concentration of minority carriers in an extrinsic semiconductor under equilibrium is
Bridge Rectifiers are preferred because
A photodiode works on the principle of
In a bridge a.c. to d.c converter using p-n diodes , if the input voltage is Vsinωt what is the peak inverse voltage across any diode?
Early effect in BJT refers to