Anna University Solved Problems

ANNA UNIVERSITY SOLVED PROBLEMS

Problem 2.12

The magnetic field strength of copper is ampere / metre. If the magnetic susceptibility of copper is - 0.8 × 10-5, calculate the magnetic flux density and magnentisation in copper.

Given data

Magnetic field strength H = 106 Am-1

Magnetic susceptibility of copper χ = -0.8 × 10-5

Solution

Problem 2.13

A magnetic field of 1800 ampere/metre produces a magnetic flux of 3 × 10-5 weber in an iron bar of cross sectional area 0.2 cm2. Calculate magnetic permeability.

Given data

Magnetizing field H = 1800 Am-1

Magnetic flux ϕ = 3 × 10-5 weber

Area of cross section A = 0.2 cm2 = 0.2 × 10-4 m2

Solution

Magnetic flux density B = ϕ/A

Substituting the given values, we have

Problem 2.14

The saturation magnetic induction of nickel is 0.65 weber / metre2. If the density of nickel is 8906 kg / m3 and atomic weight is 58.7, calculate the magnetic moment of the nickel atom in Bohr magneton. 

Given data

Magnetic induction of nickel B = 0.65 wb m-2

Density of Nickel ρ = 8906 kg m-3

Atomic weight (M) - 58.7

μo = 4π × 10-7 Hm-1

Avagadro's number N = 6.023 × 1026

Solution

We know that B = Nμo μm

N is the number of atoms per unit volume (atoms/m3)

Substituting the given values, we have

Problem 2.15

A paramagnetic material has bcc structure with a cube edge of 2.5 Å. If the saturation value of magnetisation is 1.8 × 106 ampere / metre. Calculate the average magnetisation contributed per atom in Bohr magneton. 

Given data

Interatomic distance a = 2.5 Å = 2.5 × 10-10 m

Magnetisation M = 1.8 × 106 Am-1

Electronic charge 'e' = 1.6 × 10-19 coulomb

Planck's constant h = 6.625 × 10-34 Js

Solution

Number of atoms per unit volume

= 1.52 Bohr magneton