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प्रश्न
Define self-inductance of a coil interms of
- magnetic flux and
- induced emf
उत्तर
Self-inductance or simply inductance of a coil is defined as the flux linkage of the coil when 1A current flows through it.
When the current i changes with time, an emf is induced in it. From Faraday’s law of electromagnetic induction, this self-induced emf is given by
`epsilon = - ("d"("N"Φ_"B"))/"dt" = - ("d"("Li"))/"dt"`
`therefore epsilon = - "L" "di"/"dt"` or L = `(- epsilon)/("di"//"dt")`
The negative sign in the above equation means that the self-induced emf always opposes the change in current with respect to time. If `"di"/"dt"` = 1 As-1, then L = - ε.
Inductance of a coil is also defined as the opposing emf induced in the coil when the rate of change of current through the coil is 1 A s-1.
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संबंधित प्रश्न
A circular coil with a cross-sectional area of 4 cm2 has 10 turns. It is placed at the centre of a long solenoid that has 15 turns/cm and a cross-sectional area of 10 cm2. The axis of the coil coincides with the axis of the solenoid. What is their mutual inductance?
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Assuming that the length of the solenoid is large when compared to its diameter, find the equation for its inductance.
Show that the mutual inductance between a pair of coils is same (M12 = M21).
Two air core solenoids have the same length of 80 cm and same cross–sectional area 5 cm2. Find the mutual inductance between them if the number of turns in the first coil is 1200 turns and that in the second coil is 400 turns.
A long solenoid having 400 turns per cm carries a current 2A. A 100 turn coil of cross-sectional area 4 cm2 is placed co-axially inside the solenoid so that the coil is in the field produced by the solenoid. Find the emf induced in the coil if the current through the solenoid reverses its direction in 0.04 sec.
The solenoids S1 and S2 are wound on an iron-core of relative permeability 900. The area of their cross-section and their length are the same and are 4 cm2 and 0.04 m, respectively. If the number of turns in S1 is 200 and that in S2 is 800, calculate the mutual inductance between the coils. The current in solenoid 1 is increased from 2A to 8A in 0.04 second. Calculate the induced emf in solenoid 2.
