An electric grinding wheel rotates for sometime after the power is turned off, but an electric drilling machine stops after few seconds of turning of fthe power.Why?

Why a fan continues to rotate for sometime even after it is switched off ?

A substance of mass M kg requires a power input of P wants to remain in the molten state at its melting point. When the power source is turned off, the sample completely solidifies in time t seconds. The latent heat of fussion of the substance is …….

Why do blades of an electric fan continue to rotate for some time, after the current is switched off ?

A wheel is mounted on a stationary axle starts from rest and is given by the following angular acceleration : alpha = 9 - 12 t (in SI unit ) where t is the time after the wheel begins to rotate . Find the number of revolutions that the wheel turns before it stops ( and begins to turn in the opposite direction ) .

When is more power delivered to a light bulb, just after it is turned on and the glow of the filament is increasing or after it has been ON for a few seconds and the glow is steady?

Raman is a student of class X. Raman's mother was making tea in an old electric kettle having metal case. She switched on the power supply to the electric kettle. When Raman's mother touched the metal case of working electric kettle unknowingly, she got a severe electric shock. Raman put off the main switch quickly. After removing the kettle plug from socket, Raman found that the connecting cord was torn where it touched the metal case of the kettle. He also found that though the red and black wires of connecting cord were firmly connected to the two lower terminals of the power plug but the green wire of cord was not connected to the upper terminal of the plug. Raman replaced the torn connecting cord and also connected the three wires fo cord firmly to the power plug terminals. (a) Why did Raman put off the main switch quickly ? (b) What name is given to (i) red wire (ii) black wire, and (iii) green wire, of the connecting cord ? (c) Which wire, red, black or green, touched the metal case of electric kettle when Raman's mother got electric shock ? (d) Which safety device was not working in electric kettle circuit which could have prevented the electric shock ? (e) What values are displayed by Raman in this incident ?

A thermal power plant produed electric power of 600kW at 4000V, which is to be transported to a place 20 km away form the power plant for consumer's usage. It can be transported either directly with a cable of large current carrying capacity or by sing a combination of step-up and step-down transfprmers at the two ends. THe drawback of the direct transmission is the large energy dissipation. In the method wsing transformers, the dissipatiion is much smaller. In this method a step-up transformers is used at the plant side so that the current is reduced to a smaller value. At the consumers'end, a step-down transformer is used to supply power to the consumers at the specified lower voltage. It is reasonable to assume that the power cable is purely resostive and the transformers are ideal with power factor unity. All the currents and voltagementioned are values. In the method using the transformers assume that the ratio of the number of turns in the primary to that in the secondary in the step-up transformer is 1:10 if the power to the consumers has to be supplied at 200V, the ratio of the number of turns in the primary to that in the secondary in the step-down transformer is

An electric motor rotates a wheel at a constant angular velocity (omega) while opposing torque is tau . The power of that electric motor is