Slide 1

Amperes circuit law It states that, the line integral of magnetic field intensity, around any closed path is equal to, the current enclosed by that path

Application of Amperes circuital law

Magnetic field(H) (Magnetic field Intensity ) due to infinite wire , which carrying the current I By Amperes circuital lawWe know that Magnetic field due to current carrying wire have component only.

- Magnetic field in direction

- unit vector in direction

The differential length ( ) in spherical co- ordinate system:

- radius of circular path around the wire

- Small angle created by the arch

. 1

. 3

. 2Eqn.2 and Eqn.3 in Eqn.1

Magnetic field (H) due to infinitely long co-axial transmission line. Consider a infinite long co-axial transmission line as shown in figure It consist of two cylinders The inner cylinder radius is a and it carries current I The outer cylinder has inner radius b, and the outer radius c.It carries current - IBy Amperes circuit lawConsider the circular path of radius r- Current enclosed by the closed path

. 1

. 3

. 2Eqn.2 and Eqn.3 in Eqn.1

(i) If a < r < bBy Amperes circuit law

(ii) If r < a

Current enclosed by the closed path I =

Cross -sectional area

Cross -sectional area

We know that

..4..5Eqn.5 in Eqn.4

(iii) If r is such that: b < r < C- Current carried by the inner cylinder - Current carried by the part of the outer cylinder

By Amperes circuit law

Cross sectional areaCross sectional area.7.8Eqn.5,Eqn.8 in Eqn.7

Current enclosed by the closed path =

Thus dipole are formed when an eclectic field is applied on dielectrics