Advertisements
Advertisements
Question
The self inductance L of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as ______.
Options
l and A increase.
l decreases and A increases.
l increases and A decreases.
both l and A decrease.
Advertisements
Solution
The self inductance L of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as l decreases and A increases.
Explanation:
The self inductance L of a solenoid depends on various factor like geometry and magnetic permeability of the core material.
L = μrμ0 N2 Al
Where n = N/l (no. of turns per unit length)
- No. of turns: Larger the number of turns in solenoid, larger is its self inductance.
- Area of cross-section: Larger the area of cross-section of the solenoid, larger is its self inductance.
- Permeability of the core material. The self inductance of a solenoid increases μr times if it is wound over an iron core of relative permeability μr.
The long solenoid of cross-sectional area A and length l, having A turns, filled inside of the solenoid with a material of relative permeability (e.g., soft iron, which has a high value of relative permeability) then its self inductance is L = μrμ0 N2 A/l
So, the self inductance L of a solenoid increases as l decreases and A increases because L is directly proportional to the area and inversely proportional to length.
Important point: The self and mutual inductance of capacitance and resistance depend on the geometry of the devices as well as permittivity/ permeability of the medium.
APPEARS IN
RELATED QUESTIONS
Define self-inductance. Write its SI units.
A constant current i is maintained in a solenoid. Which of the following quantities will increase if an iron rod is inserted in the solenoid along its axis?
(a) magnetic field at the centre
(b) magnetic flux linked with the solenoid
(c) self-inductance of the solenoid
(d) rate of Joule heating.
An average emf of 20 V is induced in an inductor when the current in it is changed from 2.5 A in one direction to the same value in the opposite direction in 0.1 s. Find the self-inductance of the inductor.
An inductor-coil carries a steady-state current of 2.0 A when connected across an ideal battery of emf 4.0 V. If its inductance is 1.0 H, find the time constant of the circuit.
What are the values of the self-induced emf in the circuit of the previous problem at the times indicated therein?
The magnetic potential energy stored in a certain inductor is 15 mJ, when the current in the inductor is 40 mA. This inductor is of inductance ____________.
Consider a solenoid carrying supplied by a source with a constant emf containing iron core inside it. When the core is pulled out of the solenoid, the change in current will ______.
A toroidal solenoid with air core has an average radius 'R', number of turns 'N' and area of cross-section 'A'. The self-inductance of the solenoid is (Neglect the field variation cross-section of the toroid)
Magnetic flux of 12 microweber is linked with a coil. When current of 3 mA flows through it, the self inductance of the coil is ____________.
When the current in a coil changes from 2 amp. to 4 amp. in 0.05 sec., an e.m.f. of 8 volt is induced in the coil. The coefficient of self inductance of the coil is ______.
The coefficient of self inductance of a solenoid is 0.18 mH. If a core of soft iron of relative permeability 900 is inserted, then the coefficient of self inductance will become nearly ______.
Energy needed to establish an alternating current I in a coil of self-inductance L is
State the factors on which the magnetic coupling coefficient of two coils depends.
What is meant by magnetic coupling coefficient?
The current in a coil changes from 50A to 10A in 0.1 second. The self inductance of the coil is 20H. The induced e.m.f. in the coil is ______.
In a coil, the current changes form −2 A to +2 A in 0.2 s and induces an emf of 0.1 V. The selfinductance of the coil is ______.
Two inductor coils with inductance 5 mH and 15 mH are connected in parallel. The resultant inductance of the combination of the two coils is ______.
The current flowing through an inductor of self inductance ‘L’ is continuously increasing at constant rate. The variation of induced e.m.f. (e) versus `((dI)/(dt))`is shown graphically by:
