A motor having an armature of resistance `2Omega` is designed to operate at `220 V` mains. At full speed, it devlops a back e.m.f. of `210V`. When the motor is running at full speed, the current in the armature is

A motor having an armature of resistance 2.0 Omega operates on 220 V mains. At full speed, it develops a back emf of 210 V. Find the current in the armature just when the motor is switched on (assuming that no starter is used) and when running at full speed. Also fined the efficiency of the motor at full speed.

A motor having an armature of resistance 2.0 ohm operates on 220 V mains. At its full speed, it develops a back e.m.f. of 210 V. Find the currents in the armature when motor is switched on and when running at full speed. What is the efficiency ot the motor at full speed ?

when the speed of a dc motor increase the armature current

A simple electric motor has an armature resistance of 1Omega and runs from a dc source of 12 volt . When running unloaded it draws a current of 2 amp . When a certain load is connected , its speed becomes one-half of its unloaded value . The new value of current drawn

A motor has an armature resistance of 4 ohm. On a 240 V supply and a light load, the motor speed is 200 rpm and the armature current is 5 A Calculate the motor speed at a full load. When armature current is 20 A.

A generator develops an e.m.f. of 120 V and has a terminal potential difference of 115 V, when the amature current is 25 A. What is the resistance of the armature ?

A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 Omega . When an alternating e.m.f of 220 V at 50 c.p.s. is applied to it, then the wattless component of the current in the circuit is

A fan operates at 200 volt (DC) consuming 1000W when running at full speed . It's internal wiring has resistance 1 Omega . When the fan runs at full speed , its speed becomes constant. This is because the torque due to magnetic field inside tha fan is balanced by the torque due to air resistance on the blades of the fan and torque due to friction between the fixed part and the shaft of the fan. The electrical power going into the fan is spent (i) in the internal resistance as heat, call it P_(1)(ii) in doing work against internal friction and air resistance producing heat, sound etc. call it P_(2) . When the coil of fan rotates, an emf is also induced in the coil. This opposes the external emf applied to snd the current into the fan. This emf is called back-emf,call it 'e' . Answer the following questions when the fan is running at full speed. The current flowing into the fan and the value of back emf e is

The armature of a generator of resistance 1Omega is rotated at its rated speed and produces 125 V without load and 115 V with full load. The current in the armature coil is