Fig. shows the class B push-pull circuit. The d.c. power drawn under zero signal conditions is
Question 2
A semiconductor is formed by __________ bonds.
Question 3
Class AB operation is often used in power (large signal) amplifiers in order to_______.
Question 4
In a CE (common emitter) transistor, VCC = 12 V and the zero signal collector current is 1 mA. Determine the operating point when collector load (RC) is 6 kΩ
Question 5
For the emitter follower circuit shown in Fig., the voltage gain of the emitter follower circuit is
Question 6
Class…………………operation has no collector current when no signal is applied.
Question 7
The most costly coupling is………………. coupling.
Question 8
For d.c. generator if the brushes are given a small amount of forward shift, the effect of armature reaction is
Question 9
A 220V d.c. shunt motor takes a total current of 80A and runs at 800 r.p.m. The resistance of shunt field is 50Ω and that of armature 0.1Ω The iron and friction losses amount to 1600W. What is the shaft torque?
Question 10
Which of the following information available on name plate of a motor?
Question 11
At starting, the windings of a 230 V. 50 Hz, split-phase induction motor have the following parameters: The phase angle between main winding current and starting winding current is
Question 12
A 4-pole, 50 Hz single-phase induction motor has a slip of 5%. The speed of the motor will be …………..
Question 13
The full load slip of a 4-pole, 50Hz, 3-phase induction motor rotating at 1410 r.p.m is __________.
Question 14
For a given load, the armature current of a synchronous motor will be minimum for ………….. power factor.
Question 15
The conditions of an induction motor at no-load resemble those of a transformer whose secondary is…………………….
Question 16
A 3-phase induction motor with star connected rotor has an induced e.m.f. of between slip rings at standstill on open circuit with normal voltage applied to the stator. The resistance and standstill reactance of each rotor phase are and respectively. The current per phase in the rotor when at standstill and connected to a star-connected rheostat of resistance and reactance per phase is
Question 17
A 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are and respectively. The ratio of maximum torque to full-load torque is
Question 18
A transformer has as iron loss at full-load. The iron loss at half full-load will be………………
Question 19
A source of internal resistance is connected to a load of through a transformer. For maximum power transfer, the turns ratio of the transformer should be
Question 20
A single-phase transformer has a primary resistance and inductive reactance of and respectively. The secondary values are and respectively. The equivalent impedance of the transformer referred to primary side is
Question 21
For making capacitors, it is better to select a dielectric having_________.
Question 22
A charge of passes through a solution of copper sulphate. The number of ions liberated from the electrolyte is
Question 23
The magnetic field energy in an inductor changes from maximum value to minimum value in 5m sec when connected to an a.c. source. The frequency of the source is:
Question 24
Which one of the following is a valid value of coefficient of coupling between two inductors?
Question 25
A circular disc 10 cm in diameter rotates at 1800 rev/mm about an axis through its centre and at right angles to disc. A uniform magnetic field of 1 is perpendicular to the disc. The potential difference between the axis of the disc and rim is
Question 26
The magnetic flux density in an air-cored coil is With a cast iron core of relative permeability 100 inserted, the flux density will become
Question 27
The flux through each turn of a 100-turn coil is (t3 – 2t) m Wh, where ‘t’ is in seconds. Find the magnitude of the induced emf at t = 2 s.
Question 28
The power of a heater is 500 W at What will be its power at Temperature coefficient of resistance is
Question 29
An energy meter having a meter constant of 1200 rev. per kWh is found to make 5 revolutions in 75 seconds. The load power is
Question 30
A moving coil instrument gives full-scale deflection for 1 mA and has a resistance of If a resistance of is connected in parallel with the instrument, what is the maximum current it can measure?
Question 31
A rise in temperature is observed in a conductor by passing a current. When the current is doubled, the rise in temperature will be
Question 32
In the circuit shown in figure, the battery has negligible internal resistance. The power supplied by the battery is
Question 33
In the circuit shown in figure, the cell has an internal resistance of . The heat produced in coil is 32 cal/sec. The heat produced in one second in coil is
Question 34
The current through a resistor has a wave. form shown in Figure. The reading shown by hot-wire ammeter will be
Question 35
If a load consumes 1000 W at a lagging power factor of 0.8, then apparent power drawn by the load is
Question 36
If the load connected to the 3-phase generator shown in figure has a leading p.f. of cos ϕ, then angle between VRY and IR is …………
Question 37
A voltage source has a terminal voltage of 28 V when its terminals are open-circuited. When a load is connected across the terminals, the terminal voltage drops to 24 V. What is the internal resistance of the source?
Question 38
Find Norton equivalent current to the left of terminals x-y in Figure.
Question 39
A 5 A source has a shunt internal resistance of . The maximum power that can be delivered to a load is
Question 40
When a network is loaded by a resistance equal in value to its Norton resistance, the Norton current is IN. The current through the load will be
Question 41
In a series R-L circuit supplied from a sinusoidal voltage source, voltage across R and L are 3 V and 4 V respectively. The supply voltage is then
Question 42
A tank circuit consists of
Question 43
If the source frequency in figure is low, then, ………………..
Question 44
In the circuit shown below if R3 is greater than R1 and R1 = R2. How will the voltage V1 and V2 change when the switch is closed for Constant input voltage V?
Question 45
The transient currents are due to ________.
Question 46
Which set of rules are to be verified on completion of wiring on any new installation?
Question 47
Which of the following devices can be used to test the windings of an inductor for continuity?
Question 48
Which among the following information is required for a good estimation? I. Availability of products II. Sources of production, vendor selection III. New products and their quality IV. Prices and the discounts provided for each product
Question 49
A lamp having mean spherical candle power 800 is suspended at a height of 10m. Calculate the illumination just below the lamp.
Question 50
Which of the following applications needs frequent starting and stopping of electric motor ?
Question 51
The three conductors of a 3-phase line are arranged at the corners of a triangle of sides 2 m, 2.5 m and 4.5 m. The conductors are regularly transposed and the diameter of each conductor is 1.24 cm. The inductance/phase/km is
Question 52
The string efficiency of a string of suspension insulators is dependent on
Question 53
For zero power factor lagging, the voltage regulation of a short transmission line is
Question 54
The nominal T circuit of a transmission line has for each phase. The generalized constant of the line is
Question 55
In a 33 kV overhead line, there are 3 units in the string of insulators. The voltage across the string is
Question 56
If safety factor is doubled, the sag of the line will
Question 57
When the length of a cable increases, its capacitance
Question 58
Which among the following functions shows the output of feedback control system? i. reference ii. output iii. input iv. feedback
Question 59
The condition for control system C(s) = τ1s + 1 /τ2s + 1 to be a lead network is that:
Question 60
Select the incorrect statement as per the closed loop control system?