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 |
 56%
Please attempt this question first.
Hints

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 |
Please attempt this question first.
Hints

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 |
Please attempt this question first.
Hints

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 |
Please attempt this question first.
Hints