How to calculate the inductance of the coil

An inductor can store magnetic energy during the flow of electric current. Its main characteristic is its inductance, which is denoted by the letter L and is measured in Henry (H). The inductance of the coil depends on its characteristics.

You will need

• the coil material and its geometrical parameters

Instruction

1. The inductance of the coil is proportional to the linear dimensions of the coil, magnetic permeability of the core and the square of the number of turns of winding. The inductance of a coilwound on a toroidal core is: L = ?0*?r*s*(N^2)/l. In this formula ?0 — magnetic constant, which is approximately equal to 1.26*(10^-6) Ng/m ?r — relative magnetic permeability of core material, which depends on the frequency), s is the cross — sectional area of the core, l is the length of the middle line of the core, N is the number of turns of the coil.
   Relative magnetic permeability and material, as well as the number of turns N are dimensionless quantities.
2. Thus, the inductance of the coil is greater, the larger the area of its cross section. This condition increases the magnetic flux through the coil when the same current.The inductance of the coil inductance in µh can be calculated also by the formula: L = L0*(N^2)*D*(10^-3). Here N is the number of turns, D is the diameter of coil in inches. The coefficient of L0 depends on the ratio of the length of the coil to its diameter. For single-layer coil it is equal to: L0 = 1/(0,1*((l/D)+0,45)).
3. If circuit coil are connected in series, their total inductance equals the sum of the inductances of all coils: L = (L1+L2+...+Ln)
   If coils are connected in parallel, the total inductance equal to: L = 1/((1/L1)+(1/L2)+...+(1/Ln))