Q.

An infinitely long straight conductor carries a current of 5 A as shown. An electron is moving with a speed of 105m/s parallel to the conductor. The perpendicular distance between the electron and the conductor is 20 cm at an instant. Calculate the magnitude of the force experienced by the electron at that instant.

Electron v=105m/s                                           [2021]

1 8×10-20N  
2 4×10-20N  
3 8π×10-20N  
4 4π×10-20N  

Ans.

(1)

The magnetic field due to a straight wire at the location of the electron is

B=μ04π·2Ir

B=10-7×2×50.2=50×10-7T(k^)

The direction is given by right-hand thumb rule.

The force on a charged particle moving in a magnetic field is

             F=q(v×B)

            F=-1.6×10-19×(105i^×50×10-7k^)

            F=8×10-20Nj^