Inductor

 inductor is a passive exectrical component an indulter typically consist of insulated wide wond into a coil, that stores energy in magnetic Field when electrical current flow's through it.

Inductor are also know as choke, coils and reactor also.inductor are usually coils  of wire.

SYMBOL OF INDUCTOR:

1.air core Inductor 

Air Core Inductor

2.iron core Inductor

3.ferrite core Inductor

4.variable core Inductor

• unit of Inductor is = Henry (H) ,mh (mili Henry), Ωh  ( micro Henry )

Whenever the current flowing through an inductor changes, a counter e.m.f is set up in it which opposes this change. This property is known as inductance

Unit for inductance is Henry (H). From above expression, we can define 1 Henry as the inductance which the coil has when the current changing at the rate of one ampere per of one volt. second I passes through the coil and sets up e.m.f

Inductive Reactance ( XL ) is given by following expression,

XL = = omega*L

TYPES OF INDUCTOR:there are three types of Inductor

1.air core Inductor

2.iron core Inductor

3. Ferrite core Inductor

1. all inductors are made by

winding a length of conductor around a core . The conductor is usually a solid copper or aluminum wire coated with enamel insulation, and the core is made either of magnetic material, such as powered iron, or of insulating material. When an inductor is wound around an insulating core, the core is used only for a support, since it has no magnetic properties. If heavy wire is used in making the inductor, a core is actually not needed; the regid loops of wire support themselves. When a magnetic core is not used, the inductor is usually referred to as an air-core inductor. 

2. iron core material features high power and inductance values but has limited high frequency capacities. They are a good choice in applications requiring low-space inductors.

 3. ferriate core are at the top of the list. However, when dealing with high inductance they are not always reliable and tend to reach their magnetic saturation level relatively quickly.

PROPERTIES OF INDUCTOR: 

-- Inductor oppose sudden change in current

-- inductor work as a electromagnet

-- inductor stores energy in magnetic field

Some important question and answer .

1. The behavior of the coil on the DC supply will be-- 

A )As a open circuit

B )As short circuit

C ) Same as on ac

D ) As a leakage circuit.                       Ans = b

2. Coupling coefficient between two coils has zero value. These coils are....

A) Full magnetic coupled

B) No inductive coupling

C) Maximum inductive coupling

D) Minimum inductive coupling.       ans= b

Explain:  the value of coupling two coils have four type

I) 0

ii) less then 0.5

iii) more than 0.5 and less than 1

iv) 1

-- if the value of coupling is zero the no inductive coupling

-- if the value of coupling is less then 0.5 then loose inductive coupling

-- if the value of coupling is more than 0.5 then tight inductive coupling

-- if the value of coupling is is 1 then Proper magnetic coupling 

3.A coil of L = 1 H inductance is connected to a source of 220 V at 50 Hz. Find the current of the coil.

A) 420 mA

B) 300 mA

C)  700 mA

D)  600 mA                                     and =  c

Explain : IL = V / XL

  XL=  2πfL  =2x3.14x50x1  = 314Ω

 220 / 314 = 0.7 A  and it's also called  700 ma

4. Four 1 mH inductors were added in parallel. Two 1 mH inductors were added to their series. State the equivalent inductance.

A) 600 MA

B) 2.5 mH

C) 2.25 mH

D) 3.75 mH                                        ans =  C

5. 1 /л Н choke will react at 50 Hz

frequency--

A)  100 ohm

B) 50 ohm

C) 25 ohm

D)  628 ohm                                ans= A

Explain : xL = 2πfL = 2× π× 50 ×1/π

              = 100 ohm

6. power factor of pure inductor is ...

A) Unity

B) Infinity

C) Zero

 D) High                                          ans = C

7. in a pure inductive circuit...

A) Kw = kva

B) Kw = kvar

C) Kva = kvar

D) Kw = kva = kvar                     Ans=C

8. Which inductor will have the lowest inductance?

A) Ferrite core inductor

B) Iron core inductor

C) Air core inductor

D) None above                             ans= c 

9. Storage energy in the  inductor has increased 4 times, its current value has definitely increased ...

A) Double

B) Half

C) 4 times

D) 2 times                                  ans= A

10. When switching of a  load is done, the cause of sparking on the contact is ...

A) 1/4 times

B) High resistance

C) High capacitance

D) High inductance                              ans= D

11. if k = .... the two coils are said to be 

                  loosely coupled

A) >0.5

B) <0.5

C) 1

D) 0                                                        ans= B 

12. The inductance of the two coils is 4 mH and 9 mH. Coupling coefficient between them is 0.5. Calculate the Mutual Induction.

A) 3 mH

B) 12 mH

C) 6.5 mH

D) 8 mH                                              ans=A

13. in a pure inductor--

A) Current leads the voltage by 90°

B) Voltage leads the current by 90°

C) Current & voltage are inphase

D)  None above                                      ans=B

14. The basic unit of measurement for inductance is -----

A)  Tesla

B) Simens

C) Henry

D) Weber                                             ans=c

15.The time constant of the inductor when the resistance increases 

A) Increase

B) Decrease

C) Remain same

D) None above                                      ans=B

16. The inductance of the coil on the DC supply will  be---- 

A) Maximum

B) Minimum

C) Zero

D) Infinity                                             ans=C

17. An inductor is a device that contains ..... energy.

A) Electromagnetic

B) Electrostatic

C) Potential

D) Kinetic                                                 ans=A

explain: 

- inductance have electromagnet energy

- capacitor have Electrostatic energy

- running object have kinetic energy

- press spring have potential energy