Two infinite plates shown in cross-section in figure carry `lamda` amperes of current out of thepage per unit width of plate. Find the magnetic field at points `P` and `Q`.

Answer

A, B, D

Explanation

`B` in the above situation is given by

Ap point P, `B_1` and `B_2` are in opposite directions.
Hence `B_P=0`
`At point `Q`, `B_1` and `B_2` are in same direction.
`Hence, `B_Q=((mu_0lamda)/2)=mu_0lamda`