The toroid is a hollow circular ring on which a large number of turns of a wire are closely wound.

Consider a toroid of an anchor ring of radius = r
Let n be the number of turns

Suppose that current I is passed through the toroid, then the magnetic field will be same at all points on toroid.

The magnetic field direction is tangent of the ring

B . L = μ0 × I

[ according to amphere's circuital law]

Total number of turns = 2 π r n

Total current = 2 π r n I

Thus, B × 2 π r = μ0 × 2 π r n I

B = μ0 n I

A solenoid is a tightly wound helical loop from a insulated wire and the length is very large compared to its radius.

A solenoid is a tightly wound helical loop from a insulated wire and the length is very large compared to its radius.

let the length of rectangular path AB = L
Total number of turns of the solenoid = n L
Total enclosed current = n L I
According to Amphere's circuital law,

B = μ0 n I

Consider a straight conductor of length L has area of cross-section A and the number of free charge Q per unit volume equal to n drifting with velocity V .

I = n A Q V

Multiplying both sides by L,

IL = n A Q V L

The direction of current flow opposite to velocity V, thus current element vector IL and V have opposite direction,

IL = ― n A Q V L

The magnetic Lorentz force having a charge Q and moving with the velocity V inside the magnetic field B is given by

f = ―Q ( V × B )

Total force on the current carrying conductor F,

F = N f

Where N is the total number of charge in the conductor , f is the force experiences each of the charge inside the conductor.

N = n × volume of conductor

N = n A L

F = n A L [ ―Q( V × B)]

= (―n A L Q V ) × B

=I L B

The strength of a covalent bond depends upon the extent of overlap. Greater the overlap,stronger is the bond. A sigma bond is formed by axial overlap of the orbitals while pi bond by the sidewise or lateral overlap. Since the axial overlap is more effective than   the sidewise overlap,greater energy is will be realised in axial ovrlap as compared to sidewise overlap. So sigma bond is stronger than pi bond.

Each lattice point represent one constituent particle of solids, which maybe an atom, molecule or ion.

Body whose size and shape are definitely fixed and remains unchanged when forces are applied.