JEE Main20202 Sep 2020Evening ShiftPhysicsMagnetic Effects of CurrentActual
A wire carrying current I is bent in the shape ABCDEFA as shown, where rectangle ABCDA and ADEFA are perpendicular to each other. If the sides of the rectangles are of lengths a and b , then the magnitude and direction of magnetic moment of the loop ABCDEFA is :
Options
- A2 a b I   along   j ^ 2 + k ^ 2
- Ba b I along j ^ 2 + k ^ 2
- C2 a b I along j ^ 5 + 2 k ^ 5
- Da b I along j ^ 5 + k ^ 5
Correct answer
A. 2 a b I   along   j ^ 2 + k ^ 2
Step-by-step solution
Loop ABCD M → 1 = ( abI ) ( k ^ ) For Loop DEFA M → 2 = ( abI ) ( j ^ ) M → = M → 1 + M → 2 ; M → = ( a b I ) ( j ^ + k ^ ) 2 a b I along j ^ 2 + k ^ 2 .