Arrange the following electromagnetic radiations in the order of increasing energy

A.Blue light    B.Yellow light

C.X-ray          D. Radio wave

A) D,B,A,C

B) A,B,D,C

C) C,A,B,D

D) B,A,D,C


An arc lamp requires a direct current of 10A at 80 V to function. If it is connected to a 220V (rms) , 50Hz AC supply, the series inductor needed for it to work is close to 

A) 80H

B) 0.08H

C) 0.044 H

D) 0.065 H


Hysteresis loops for two magnetic materials A and B are as  given below


These materials are used to make magnets for electric generators, transformer core, and electromagnet core. Then, it is proper to use

A) A for electric generators and transformers

B) A for electromagnets and B for electric generators.

C) A for transformers and B for electric generators

D) B for electromagnets and transformers


Two identical wires A and B, each of length l, carry the same current I. Wire A is bent into a circle of radius R and wire B is bent to form a square of side a. If BA and BB are the values of the magnetic field at the centers of the circle and square respectively. then the ratio $\frac{B_{A}}{B_{B}}$ is

A) $\frac{\pi^{2}}{8}$

B) $\frac{\pi^{2}}{16\sqrt{2}}$

C) $\frac{\pi^{2}}{16}$

D) $\frac{\pi^{2}}{8\sqrt{2}}$


The temperature dependence of resistance of Cu and undoped Si in the temperature range 300-400 K, is best described by

A) Linear increase for Cu, linear increase for Si

B) linear increase for Cu, exponential increase for Si

C) linear increase for Cu, exponential decrease for Si

D) Linear decrease for Cu, linear decrease for Si