Magnetic Effect of electric current

 Magnetic Field Due to Electric Current

Introduction: We are very well familiar with the concept that an electric current flowing through the conductor develops a magnetic field around it. In the last lesson, we have studied charges which are at rest, and in this chapter, we are going to see about the force due to moving charges. We are going to see the magnitude of the magnetic field due to the different elements and shapes of a conductor using some laws.

The direction of magnetic field:

Q) State Right hand thumb rule.

=> Consider a conductor in your right hand as shown in the figure below. If the thumb shows the direction of current then the curled finger shows the direction of the magnetic field at that point.

Right hand thumb rule

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Magnetic force on a charge placed in a magnetic field. (Lorentz Force)

Q) What do you mean by Lorents Force?

=>  When a charge is placed in a magnetic field, it experiences a magentic force.Let us understand it with help of certain example.

Consider a charge 'q' is placed in a magnetic field of magnitude B. It experiences a force and start moving with velocity v.The force experienced by the charge is given by,

 F_m = q ( v x B) ----(1)

where  F_m = magnetic force

q = charge

v = velocity

B = magnetic field

If a magnetic field and electric field both are present then the force on the charge id given by,

 Fnet = q[E + ( v x B)]

 Fnet = qE + q( v x B)

we know that Electrostatic force F_E = qE & Magnetic force  F_m = q ( v x B)

 Fnet =  F_E + F_m 

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Magnetic Induction B

Q) Define magnetic Induction and give it's SI Unit and Dimension.

=> From above equation (1)  we can define magnetic Induction as

Magnetic induction is said to be 1Tesla if a charge of 1 coulomb placed in magnetic field moving with velocity of 1m/s experince a force of 1N.

B =  F_m / qv

Unit of (B) = Ns /Cm or Tesla(T)

Dimension = [L⁰M¹ T^-2 I^-1]

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Related topics: Lorentz force   Force on a straight wire     Force on a arbitrary shaped wire     Cyclotron    Cyclotron accelerator   Helix   Torque due to magnetic field     Moving coil galvanometer    Biot-Savart's law    Magnetic field due to straight wire    Forces between parallel Conductors     Magnetic field due to Circular arc   magnetic field due to Circular Loop   Magnetic field on axis of a circle    Circle as a dipole   Ampere's law    Magnetic field due to solenoid    Magnetic field due to Toroid.