Physics - Study Mode

[#396] The best material for the core of a transformer is
Correct Answer

(D) Soft iron

Explanation

Solution: Soft iron provides the best material for the core of a transformer as its permeability (μ) is very high. Its hysteresis curve is of small area and its coercivity is very low.

[#397] A transformer works on the principle of
Correct Answer

(B) Mutual induction

Explanation

Solution: A transformer consists of two electrically isolated coils and operates on Faraday's principal of “mutual induction”, in which an EMF is induced in the transformers secondary coil by the magnetic flux generated by the voltages and currents flowing in the primary coil winding.

[#398] Atomic hydrogen has a life period of
Correct Answer

(D) A fraction of a second

Explanation

Solution: Atomic hydrogen is unstable and it has life period of a fraction of a second.

[#399] Rainbow is produced when sunlight fall on drops of rain. Which of the following physical phenomena are responsible for this? I.Diffusion II.Refraction III.Internal reflection
Correct Answer

(C) II and III

Explanation

Solution: Refraction and internal reflection are responsible for this physical phenomena.

[#400] Natural radioactivity was discovered by
Correct Answer

(C) Henri Becquerel

Explanation

Solution: Natural radioactivity was discovered by Henri Becquerel.