question_answer

An aluminium ring B faces an electromagnet A. The current J through A can be altered. Then which of the following statements is correct?

A)  If I decreases, A will repel B

B)  Whether I increases or decreases, B will not experience any force

C)  If I increases, A will repel B

D)  If I increases, A will attract B

Correct Answer: C

Solution :

 If I increases then magnetic field in coil will be increases and \[\overset{\to }{\mathop{B}}\,\]will acts as shown in ring B I will induce in         Such away that will opposes the increases of I in electromagnet. Hence in B direction of \[\overset{\to }{\mathop{B}}\,\]will be as shown. Hence repel B.