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

A thin prism P₁ of angle 4 ° and refractive index 1.54 ° is combined with another thin prism P₂ of refractive index 1.72 to produce dispersion without deviation. The angle of P₂ is

 

What will be the number of photons emitted per second by a 10 W sodium vapour lamp assuming that 90% of the consumed energy is converted into light [Wavelength of sodium light is 590 nm, and h = 6.63×10^-34 J –s]

 

200 MeV of energy may be obtained per fission of U²³⁵. A reactor is generating 1000 kW of power. The rate of nuclear fission in the reaction is

 

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 E, I 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

Which one of the following is not made of soft iron?

 

Two tangent galvanometer having coils of the same radius are connected in series. A current flowing in them produces deflection of 60 ° and 45 ° respectively. The ratio of the number of turns in the coils is

 

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

 

An ideal coil of 10 H is joined in serried with a resistance of 5 Ω and battery of 5 V, 2 s after joining the current flowing (in ampere) in the circuit 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