1. Which of the following are true in respect of interpoles in dc machines? Reduce armature reaction effects in interpolar region. Windings are connected in series with armature. Have the same dimensions as main poles. Select the correct answer using the code given below: (a) 1 and 2 only. (b) 2 and 3 only. (c) […]
1. Consider the following statements In a dc series generator, full-load voltage is more than the no-load voltage. In a separately excited de generator full-load voltage is more than the no-load voltage. In a dc shunt generator, full-load voltage is less than the no-load voltage. Of these statements. (a) 1, 2 and 3 are correct.
1. In a DC generator, the ripples in the generated DC are reduced by employing (a) commutator with large number of segments. (b) equalizer rings. (c) carbon brushes. (d) graphite brushes. 2. In order to ascertain whether a DC machine is lap wound or wave wound on the basis of visual observations of the armature,
1. In an electromechanical energy conversion devices (e.g. generators and motors) a small air gap is left between the stator and the rotor in order to (a) reduce the reluctance of the magnetic path. (b) increase flux density in the air gap. (c) permit mechanical clearance. (d) avoid saturation of field. 2. The EMF induced
1. The current through a resistor has a waveform as shown in Figure given below. The reading shown by a moving coil ammeter will be ……….amperes. (a) 5/√2 (b) 2.5/√2 (c) 5/π (d) 0 2. The RMS value of the voltage u(t) = 3 + 4 cos (3t) is (a) √17 (b) 5 V (c)
1. Which of the following are necessary conditions for an entire 3-phase system to be balanced? The line voltages are equal in magnitude. The phase differences between successive line voltages are equal. The impedances in each of the phases are identical. Select the correct answer using the codes given below: (a) 1, 2 and 3
1. When a sinusoidal voltage is applied across R – L series circuit having R = XL, the phase angle will be (a) 90o (b) 45o lag (c) 45o leading (d) 90o leading 2. An ac source of 200 V RMS supplies active power of 600 W and reactive power of 800 VAR. The RMS
1. The magnetic susceptibility of a paramagnetic material is (a) less than zero (b) less than one but positive (c) greater than one (d) equal to zero 2. Air exhibits (a) ferromagnetism (b) paramagnetism (c) antiferromagnetism 3. Soft magnetic materials have (a) high permeability and low coercive force (b) low permeability and high coercive force
1. Internal resistance of primary cell varies (a) inversely with the distance between electrodes (b) inversely with the surface area of electrodes (c) directly with the distance between electrodes (d) with the nature of electrodes (e) all of above except (a) 2. If the battery has zero internal resistance and the external resistance R is
1. Ohm’s law cannot be applied to the circuits consisting of (a) electronic tubes or transistors (b) non-linear elements (c) powdered iron, electric arc etc. (d) all of the above. An electric circuit, whose characteristics or properties are same in either direction (e.g. a distribution or transmission line) is called the bilateral circuit. An electric