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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Explain why the inductance of two coils connected in parallel is less than the inductance of either coil.

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प्रश्न

Explain why the inductance of two coils connected in parallel is less than the inductance of either coil.

टीपा लिहा
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उत्तर १

  1. For a parallel combination of two coils, the current through each parallel inductor is a fraction of the total current and the voltage across each parallel inductor is the same.
  2. As a result, a change in total current will result in less voltage dropped across the parallel array than for any one of the individual inductors.
  3. There will be less voltage drop across parallel inductors for a given rate of change in current than for any of the individual inductors.
  4. Less voltage for the same rate of change in current results in less inductance.
  5. Thus, the total inductance of two coils is less than the inductance of either coil.
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उत्तर २

When two inductors with inductances L1 and L2 are connected in parallel, the equivalent inductance is given by

`1/"L"_"equivalent" = 1/"L"_1 + 1/"L"_2`

which is less than the individual inductance value L1 and L2.

As a result, the inductance of two parallel coils is smaller than the inductance of either coil.

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  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 12: Electromagnetic Induction - Short Answer I

संबंधित प्रश्‍न

Define the coefficient of self-induction.


Define self-inductance. Write its SI units.


The currents flowing in the two coils of self-inductance L1 = 16 mH and L2 = 12 mH are increasing at the same rate. If the power supplied to the two coil is equal, find the ratio of  the currents ?


The currents flowing in the two coils of self-inductance L1 = 16 mH and L2 = 12 mH are increasing at the same rate. If the power supplied to the two coil is equal, find the ratio of the energies stored in the two coils at a given instant ?


Derive the expression for the self-inductance of a long solenoid of cross sectional area A and length l, having n turns per unit length.


A plot of magnetic flux (Φ) versus current (I) is shown in the figure for two inductors A and Β. Which of the two has larger value of self inductance?


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.


A magnetic flux of 8 × 10−4 weber is linked with each turn of a 200-turn coil when there is an electric current of 4 A in it. Calculate the self-inductance of the coil.


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.


A coil having inductance 2.0 H and resistance 20 Ω is connected to a battery of emf 4.0 V. Find (a) the current at the instant 0.20 s after the connection is made and (b) the magnetic field energy at this instant.


An inductor of inductance 5.0 H, having a negligible resistance, is connected in series with a 100 Ω resistor and a battery of emf 2.0 V. Find the potential difference across the resistor 20 ms after the circuit is switched on.


Consider a small cube of volume 1 mm3 at the centre of a circular loop of radius 10 cm carrying a current of 4 A. Find the magnetic energy stored inside the cube.


Answer the following question.
When an inductor is connected to a 200 V dc voltage, a current at 1A flows through it. When the same inductor is connected to a 200 V, 50 Hz ac source, only 0.5 A current flows. Explain, why? Also, calculate the self-inductance of the inductor. 


Two pure inductors each of self-inductance L are connected in series, the net inductance is ______  


Define self-inductance.


When a coil is connected to a D.C. source of e.m.f. 12 volt, then a current of 4 ampere flows in it. If the same coil is connected to a 12 volt, 25 cycle/s A.C sources, then the current flowing in it is 2.4 A. The self-inductance of the coil will be ______


When the number of turns in a coil is tripled without any change in the length of the coil, its self-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)


Two coils of wire A and B are placed mutually perpendicular as shown. When current is changed in any one coil.


The frequency of γ-rays, X-rays and ultraviolet rays are a, b and c respectively. Then, ______.


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 ______.


Choke coil works on the principle of ______.

Production of induced e.m.f. in a coil due to the changes of current in the same coil is ______.

An air-cored solenoid with length 30 cm, area of cross-section 25 cm2 and number of turns 800, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10-3s. Ignoring the variation in magnetic field near the ends of the solenoid, the average back emf induced across the ends of the open switch in the circuit would be ______.


Energy needed to establish an alternating current I in a coil of self-inductance L is


An average induced emf of 0.20 V appears in a coil when the current in it is changed from 5A in one direction to 5A in the opposite direction in 0.20 sec. Find the self induction of the coil.


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 ______.


The inductance of a solenoid L having diameter d. Let n be the number of turns per unit length. The inductance per unit length near the middle of a solenoid is ______.

(Assume that, l = current passes through the turns, µ0 = Permeability of vacuum)


Calculate the self-inductance of a coil using the following data obtained when an AC source of frequency `(200/pi)` Hz and a DC source are applied across the coil.

AC Source
S.No. V (volts) I (A)
1 3.0 0.5
2 6.0 1.0
3 9.0 1.5
DC Source
S.No. V (volts) I (A)
1 4.0 1.0
2 6.0 1.5
3 8.0 2.0

A current of 1A flows through a coil when it is connected across a DC battery of 100V. If the DC battery is replaced by an AC source of 100 V and angular frequency of 100 rad s-1, the current reduces to 0.5 A. Find

  1. the impedance of the circuit.
  2. self-inductance of coil.
  3. Phase difference between the voltage and the current.

An air-cored solenoid, 40 cm long and of cross-sectional area 5 cm2, is tightly wound with 400 turns of copper wire and carries a steady current of 10 A. (a) Calculate the self-inductance of the solenoid. (b) Find the emf induced if the current in the solenoid decreases to zero in 0.2 s.


Obtain an expression for the self inductance of a solenoid.


A toroid of a circular cross-section of radius 0.05 m has 2000 windings and a self-inductance of 0.04 H. What is (a) the current through the windings when the energy in its magnetic field is 2 × 10−6 J and (b) the central radius of the toroid?


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 ______.


A coil of self-inductance L is connected in series with a bulb and an a. c. source. Brightness of the bulb decreases when ______.


The current flowing through an inductor of self-inductance L is continuously increasing at constant rate. The variation of induced e.m.f. (e) verses dI/dt is shown graphically by figure


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 ______.


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