SELF-INDUCTION OF LONG SOLENOID

SELF-INDUCTION OF LONG SOLENOID

self- induction
self- induction of long solenoid

SELF-INDUCTION OF LONG SOLENOID this topic is important for the class 12th board examination

Self-inductance of long air-cored solenoid question may asked as –

what do you mean by the term self-induction ? Find expression for the self-inductance of long air cored solenoid .

Self-inductance of long air-cored solenoid –

Suppose a long air cored solenoid having ‘n’ number of turns per unit length . If current in the solenoid is ‘I’  the magnetic field within the solenoid B= µ0nI . If A is the area of cross-section of the solenoid , the effective flux linked with the solenoid of length ‘l’ ; ɸ=NBA……………………………….(i)

where N is the total no. of turns of the solenoid . so ɸ= n l B A …………………………………….(ii) . substituting the value of B in this equation

we get,

ɸ =n l(µ0nI ) A  = µ0n2A l I .

so , self-inductance  of solenoid L=ɸ/ I.=   µ0n2A l I / I  = µ0 n2 Al

but n= N/l

so self- inductance L= µ0 N2A/ l .

If solenoid contains a core of ferromagnetic material , having relative permeability µr then self-inductance  L=   µ0µr N2A/ l .

necessary picture of this topic  is shown above**.

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