Two mutually perpendicular to infinite wires along x-axis and y-axis carry charge densities λ1  and  λ2. The electric line of force at P is along the line y=x/3, where P is also a point lying on the same line. Find λ1/λ2.

Net electric field is P→. E→=E→1+E→2 due to vertical wire E→1=λ12πε0y in +y-directionE→2=λ22πε0x due to vertical wire in x-direction.α angle of electric field with x directiontanα=E1E2=λ1/2πε0yλ2/2πε0xor 13=λ1xλ2y  or  λ1λ2=xy3  or  λ1λ2=3