A choke is preferred to a resistance for limiting current in AC circuit because

1.  choke is cheap
2.  there is no wastage of power
3.  choke is compact in size
4.  choke is a good absorber of heat

Subtopic:  Transformer |
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As shown in the figure a magnet is moved with a fast speed towards a coil at rest. Due to this induced emf, induced current and induced charge in the coil is EI and Q respectively. If the speed of the magnet is doubled, the incorrect statement is-
1.  E increases
2.  I increases
3.  Q remains same
4.  Q decreases


Subtopic:  Faraday's Law & Lenz Law |
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Which one of the following is not made of soft iron?

1.  Electromagnet
2.  Core of transformer
3.  Core of dynamo
4.  Magnet of loudspeaker

Subtopic:  Magnetic Materials |
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A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of 4×10-5 T to a direction of 60 ° from the field will be


A rocket is fired upward from the earth surface such that it creates an acceleration of 19.6 m/s2. If after 5 s, its engine is switched off, the maximum height of the rocket from earth’s surface would be

1.  245 m
2.  490 m
3.  980 m
4.  735 m

Subtopic:  Distance & Displacement |
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