Question
Question: A long wire AB is placed on a table. Another wire PQ of mass 1.0 g and length 50 cm is set to slide ...
A long wire AB is placed on a table. Another wire PQ of mass 1.0 g and length 50 cm is set to slide on two rails PS and QR. A current of 50A is passed through the wires. At what distance above AB, will the wire PQ be in equilibrium
A
25 mm
B
50 mm
C
75 mm
D
100 mm
Answer
50 mm
Explanation
Solution
Net force on a current carrying loop in uniform magnetic field is zero. Hence the loop can't translate. So, options (3) and (4) are wrong. From Flemings left hand rule we can see that if magnetic field is perpendicular to paper inwards and current in the loop is clockwise (as shown) the magnetic force Fm on each element of the loop is radially outwards, or the loops will have a tendency to expand.
