Test: Electromagnetic Fields Theory- 3 - Electrical Engineering (EE) MCQ

# Test: Electromagnetic Fields Theory- 3 - Electrical Engineering (EE) MCQ

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## 20 Questions MCQ Test SSC JE Electrical Mock Test Series 2025 - Test: Electromagnetic Fields Theory- 3

Test: Electromagnetic Fields Theory- 3 for Electrical Engineering (EE) 2024 is part of SSC JE Electrical Mock Test Series 2025 preparation. The Test: Electromagnetic Fields Theory- 3 questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Electromagnetic Fields Theory- 3 MCQs are made for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Electromagnetic Fields Theory- 3 below.
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Test: Electromagnetic Fields Theory- 3 - Question 1

### The classical analogous of a simple lever is______;

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 1

A lever maintains the same level of work required to lift something as if it weren't used.

W = Fd

The amount of force required is decreased, but the distance that you need to move is increased while the work remains constant.

The amount of Power going into a transformer is the same amount that is coming out (not accounting for losses)

Power = Voltage × Current

P = VI

You can increase the voltage of a transformer, but the current will vary inversely as the power remains unchanged.

Test: Electromagnetic Fields Theory- 3 - Question 2

### What is the relation between magnetic field intensity H and magnetic flux density?

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 2

The relation between magnetic field intensity (H) and magnetic flux density (B) is

B = μ H Wb/m2

Where, μ is the magnetic permeability

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Test: Electromagnetic Fields Theory- 3 - Question 3

### A 1 ϕ, 120 V, 60 Hz supply is connected to the coil as shown below. The coil has 200 turns. What is the maximum flux developed by the coil?

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 3

Given that, E = 120 V

Number of turns (N) = 200

We know that,

Test: Electromagnetic Fields Theory- 3 - Question 4

The magnetic field intensity in a material whose relative permeability is 1 when the flux density is 0.005 T is:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 4

The relation between magnetic field intensity (H) and magnetic flux density (B) is

B = μ H

Test: Electromagnetic Fields Theory- 3 - Question 5

Curie point is:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 5

The Curie temperature or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, to be replaced by induced magnetism.

Test: Electromagnetic Fields Theory- 3 - Question 6

Two magnetic cores A and B made up of materials with relative permeability 300 and 400 respectively have identical physical dimension then_______.

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 6

The reluctance is inversely proportional to the relative permeability. Hence material with lesser permeability will offer more reluctance.

Here core A has lesser permeability and hence offer more reluctance.

Test: Electromagnetic Fields Theory- 3 - Question 7

Paramagnetic substances are:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 7

Those substances which are weekly magnetised when placed in an external magnetic field in the same direction as the applied field are called paramagnetic substances. They tend to move from weaker to the stronger part of the field. The magnetism exhibited by these substances is called Para magnetism.

Examples: Aluminium, platinum, sodium, calcium

Test: Electromagnetic Fields Theory- 3 - Question 8

What is the energy stored in the magnetic field at a solenoid of 40m long and 4m diameter wound with 100 turns of wire carrying a current at 20 A?

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 8

The inductance of a solenoid is given by,

Energy stored in an inductor is given by,

Test: Electromagnetic Fields Theory- 3 - Question 9

Material subjected to rapid reversal of magnetism should have:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 9

Permeability is the measure of the ability of a material to support the formation of a magnetic field within itself. It is the degree of magnetization that a material obtains in response to an applied magnetic field. Hence permeability should be high to rapid reversal of magnetism.

Hysteresis loss is caused by the magnetization and demagnetization of the core as current flows in the forward and reverse directions. Hence it should be low.

Test: Electromagnetic Fields Theory- 3 - Question 10

Calculate the reluctance of a magnetic coil which is wounded uniformly on an iron core provided that the relative permeability of the iron is 1400. Also, the length of the magnetic circuit is 70 cm and the cross-sectional area of the core is 5 cm2.

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 10

Reluctance of a magnetic coil is given by,

Test: Electromagnetic Fields Theory- 3 - Question 11

The unit of Magmetomotive Foce (MMF) is

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 11

The current flowing in an electric circuit is due to the existence of electromotive force similarly magnetomotive force (MMF) is required to drive the magnetic flux in the magnetic circuit. The magnetic pressure, which sets up the magnetic flux in a magnetic circuit is called Magnetomotive Force. The SI unit of MMF is ampere-turn (AT)

Test: Electromagnetic Fields Theory- 3 - Question 12

Flux in a magnetic circuit is analogous to:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 12

Test: Electromagnetic Fields Theory- 3 - Question 13

Find the magnetic field strength if a coil of 180 turns is wound uniformly over a wooden ring having a mean circumferences of 0.5 m and with current of 4A through the coil

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 13

Given that, Number of turns (N) = 180

Length (l) = 0.5 m

Current (I) = 4 A

Magnetic field strength (H) is given by,

Test: Electromagnetic Fields Theory- 3 - Question 14

Temporary magnets are used in

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 14

Temporary magnets are made from soft metals and only retain their magnetism while near a permanent magnetic field or electronic current. Common temporary magnets include nails and paperclips, which can be picked up or moved by a strong magnet

Temporary magnets are used in telephones, loud speakers, generators and electric motors

Test: Electromagnetic Fields Theory- 3 - Question 15

The magnetism left in the iron after exciting field has been removed is known as

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 15

The ability of a coil to retain some of its magnetism within the core after the magnetisation process has stopped is called retentivity, while the amount of flux density still remaining in the core is called residual magnetism

Test: Electromagnetic Fields Theory- 3 - Question 16

The magnetic field strength on the axis of a short solenoid is:

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 16

The magnetic field strength (H) of a short solenoid is given by,

Where N is the number turns

I is the current in ampere

L is the length

From the above expression we can observe that the magnetic field strength is proportional to ampere turns and inversely proportional to length.

Test: Electromagnetic Fields Theory- 3 - Question 17

The electric field intensity due to an infinite plane sheet of charge is

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 17

The electric field intensity due to an infinite plane sheet of charge is given by,

Thus, the field is uniform and does not depend on the distance from the plane sheet of charge.

Test: Electromagnetic Fields Theory- 3 - Question 18

What is the unit of reciprocal of reluctance?

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 18

Permeance is the reciprocal of reluctance. In a magnetic circuit, permeance is a measure of the quantity of magnetic flux for a number of current-turns.

The SI unit of magnetic permeance is webers per ampere-turn that is H (henry).

Test: Electromagnetic Fields Theory- 3 - Question 19

Which of the following correctly defines relations between magnetic flux density and distance?

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 19

We know that, B = μH

Magnetic field density is inversely proportional to length. Hence magnetic flux density increases with decrease in distance.

Test: Electromagnetic Fields Theory- 3 - Question 20

Ferrites are types of

Detailed Solution for Test: Electromagnetic Fields Theory- 3 - Question 20

Ferrites are usually ferrimagnetic ceramic compounds derived from iron oxides. Like most of the other ceramics, ferrites are hard, brittle, and poor conductors of electricity.

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## SSC JE Electrical Mock Test Series 2025

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