Question

Four wires each of length 2.0 metres are bent into four loops P, Q, R and S and then suspended into uniform magnetic field. Same current is passed in each loop. Which statement is correct?

• A. Couple on loop P will be the highest
• B. Couple on loop Q will be the highest
• C. Couple on loop R will be the highest
• D. Couple on loop S will be the highest

Answer 1

The correct option is D Couple on loop S will be the highest

Couple of force on loop S will be maximum because for same perimeter the area of loop will be maximum and magnetic moment of loop $=i\times A$. So, it will also be maximum for loop S.