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)
Life becomes much easier during the power outage if you have a generator, and if the generator is portable and makes very minimum noise, then it will be the best companion to easily carry along to the camping site to recharge your electronics. These all advantages are offered by the inverter generators. In this article,
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
1. The specific energy consumption of a train depends on which of the following? (a) Acceleration and retardation (b) Gradient (c) Distance covered (d) All of the above 2. The friction at the track is proportional to (a) 1/speed (b) speed (c) 1/speed2 (d) none of the above 3. The air resistance to the movement
1. The travelling speed of cranes varies from (a) 20 to 30 m/s (b) 10 to 15 m/s (c) 5 to 10 m/s (d) 1 to 2.5 m/s 2. Which of the following motors is preferred when quick speed reversal is the main consideration ? (a) Squirrel cage induction motor (b) Wound rotor induction motor