Electrical Engineering · Question Bank

Magnetic Circuits

84 questions · page 2 of 5. Answer in your head first, then check the solution.

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TypeAll 84Problem solving 28Objective 56
DifficultyAll 84Easy 78Medium 5Hard 1
#21📜 EE Pre-Board March 2014📘 PowerhouseEasy
A wire 36 inches long is carrying a current of 1,200 A. Find the flux density in gauss at a point 12 inches from the wire.
A2.4
B7.87
C6.31
D5.52
#22📜 EE Pre-Board March 2014📘 PowerhouseEasy
An air gap 1.1 mm long and 40 cm² in cross-section exists in a magnetic circuit. Determine the mmf required to create a flux of \(10 \times 10^{-4}\) Wb in the air gap.
A2.1885 AT
B21.885 AT
C218.85 AT
D2,188.5 AT
#23📜 EE Pre-Board August 2014📘 PowerhouseEasy
Two long straight conductors each carrying an electric current of 5A are kept parallel to each other at a separation of 2.5cm. Calculate the magnitude of magnetic force experienced by 10cm of a conductor.
A\(2 \times 10^{-3}\) N
B\(2 \times 10^{-4}\) N
C\(2 \times 10^{-5}\) N
D\(2 \times 10^{-6}\) N
#24📜 EE Pre-Board August 2014📘 PowerhouseEasy
When the relative permeability of a material is slightly less than 1, it is called_____ material.
Anon-magnetic
Bparamagnetic
Cferromagnetic
Ddiamagnetic
#25📜 EE Pre-Board August 2014📘 PowerhouseEasy
A magnetic field exist around
Acopper
Bmoving charges
Ciron
Daluminum
#26📜 EE Pre-Board August 2014📘 PowerhouseEasy
A material commonly used for shielding or screening magnetism is
Abrass
Baluminum
Ccopper
Dsoft iron
#27📜 EE Pre-Board August 2014📘 PowerhouseMedium
An iron core has a cross-section of 500 mm² and a length of 100 cm. A magnetizing force of 500 AT in it produces a magnetic flux of 400 μWb. Determine the relative permeability of the material.
A1,275
B1,250
C1,225
D1,200
#28📜 EE Pre-Board March 2015📘 PowerhouseEasy
In the Fleming’s left hand rule, thumb always represents
Avoltage
Bcurrent
Cdirection of force on conductor
Dmagnetic field
#29📜 EE Pre-Board March 2015📘 PowerhouseEasy
A horizontal powerline carries a current of 90 A. Compute the magnetic field at a point 1.5 m below the line.
A\(1.2 \times 10^{-5}\) T
B\(1.2 \times 10^{-4}\) T
C\(1.2 \times 10^{-3}\) T
D\(1.2 \times 10^{-2}\) T
#30📜 EE Pre-Board March 2015📘 PowerhouseEasy
A wire length 1 m carries a current of 10 A perpendicular to a field of flux density 0.5 T. Determine the magnitude of the force on the wire.
A5 N
B50 N
C10 N
D100 N
#31📜 EE Pre-Board March 2015📘 PowerhouseEasy
Two conductors carrying 50 amperes and 75 amperes respectively are placed 10 cm apart. Calculate the force between them per meter.
A0.075 N/m
B100 N/m
C0.0075 N/m
D10 N/m
#32📜 EE Pre-Board August 2015📘 PowerhouseEasy
The core of a certain magnetic circuit has a length of 5 cm and the inductance of the coil is 10 mH. What is the inductance of the same if the number of turns is reduced to 1/2 of the original? All other factors are unchanged.
A20 mH
B10 mH
C2.5 mH
D5.0 mH
#33📜 EE Pre-Board August 2015📘 PowerhouseEasy
An electromagnet has an air gap of 3 mm and the flux density in the gap is 1.257 Wb/m² . Calculate the ampere-turns required for the gap.
A2000
B2,500
C3,000
D4,000
#34📜 EE Pre-Board August 2015📘 PowerhouseEasy
All magnetic fields originates from
AMoving electric charges
BIron atoms
Cmagnetic domain
Dpermanent magnets
#35📜 EE Pre-Board August 2015📘 PowerhouseEasy
Two long straight conductors each carrying an electric current of 5A are kept parallel to each other at a separation of 2.5cm. Calculate the magnitude of magnetic force experienced by 10cm of a conductor.
A\(5 \times 10^{-5}\) N
B\(4 \times 10^{-5}\) N
C\(3 \times 10^{-5}\) N
D\(2 \times 10^{-5}\) N
#36📜 EE Pre-Board March 2016📘 PowerhouseEasy
The permeability of a material means
AStrength of permanent magnet
BStrength of an electromagnet
CThe magnetization left in the iron after exciting field has been removed.
DThe conductivity of a material for magnetic lines of force
#37📜 EE Pre-Board March 2016📘 PowerhouseEasy
A current of 10 A is flowing in a flexible conductor of length 1.5 m. A force of 15 N acts on it when it is placed in uniform field of 2 T. Calculate the angle between the magnetic field and the direction of the current.
A90°
B60°
C45°
D30°
#38📜 EE Pre-Board March 2017📘 PowerhouseEasy
What determines the direction of force in a conductor?
ALenz law
BFaraday’s law
CLeft hand rule
DRight hand rule
#39📜 EE Pre-Board March 2017📘 PowerhouseMedium
An air cored toroidal coil has 450 turns, a mean diameter of 300 mm and a cross-sectional area of 300 mm². Determine the self-inductance of the coil.
A\(81 \times 10^{-4}\) H
B\(8.1 \times 10^{-4}\) H
C\(0.81 \times 10^{-4}\) H
D\(0.081 \times 10^{-4}\) H
#40📜 EE Pre-Board March 2017📘 PowerhouseEasy
The flux produced in the air gap between two electromagnetic pole faces is \(6 \times 10^{-2}\) Wb. The length of the air gap is 1.4 cm and the cross-sectional area of the gap is 0.3 m². Find the magnetic field intensity.
A\(153.2 \times 10^{3}\) AT/m
B\(155.2 \times 10^{3}\) AT/m
C\(157.2 \times 10^{3}\) AT/m
D\(159.2 \times 10^{3}\) AT/m

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