Basic Electrical Engineering Questions and Answers – Magnetomotive Force and Magnetic Field Strength

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This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Magnetomotive Force and Magnetic Field Strength”.

1. What is a permeable substance?
a) Any good conductor
b) Any bad conductor
c) Any strong magnet
d) Any substance through which the magnetic lines of force can pass easily
View Answer

Answer: d
Explanation: A permeable substance is one through which the magnetic lines of force can pass easily.
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2. Materials having good retentivity are?
a) Strong magnets
b) Weak magnets
c) Temporary magnets
d) Permanent magnets
View Answer

Answer: d
Explanation: Materials with good retentivity are permanent magnets because they can retain magnetism even when no external magnetic field present.

3. Magnetic field exists along which of the following?
a) Moving charges
b) Stationary charges
c) Copper
d) Iron
View Answer

Answer: a
Explanation: Moving charges have a magnetic field associated with them because they have magnetic flux lines associated with it.
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4. Magnetomotive force is equal to__________________
a) current * number of turns
b) current / number of turns
c) current / number of turns per unit length
d) current * number of turns per unit length
View Answer

Answer: a
Explanation: MMF is ability to produce flux and is equal to product of current flowing and number of turns.

5. Unit of MMF is ______________
a) A/m
b) A-m
c) A
d) unitless
View Answer

Answer: c
Explanation: MMF is equal to the product of current flowing and number of turns.
unit of Magnetomotive force = unit of current = A or ampere.
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6. When a bar magnet is broken into two pieces, which of the following are true?
a) The magnet loses its magnetism
b) The magnet has only north pole left
c) The magnet has only south pole left
d) The magnet turns into two new bar magnets
View Answer

Answer: d
Explanation: When a bar magnet is broken into two pieces, it forms two different bar magnets. This happens because the broken pieces of the magnet form a separate north and south pole for itself as monopoles do not exist.

7. When an electric current flows into the page, what is the direction of the magnetic field?
a) Clockwise
b) Anti-clockwise
c) Cannot be determined
d) Parallel to the current
View Answer

Answer: a
Explanation: When the current flows into the page, the magnetic field is clockwise because of the right hand thumb rule, we orient our thumb into the page and our fingers curl in the clockwise direction.
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8. When an electric current flows out of the page, what is the direction of the magnetic field?
a) Clockwise
b) Anti-clockwise
c) Cannot be determined
d) Parallel to the current
View Answer

Answer: b
Explanation: When the current flows out of the page, the magnetic field is anti-clockwise because of the right hand thumb rule, we orient our thumb out of the page and our fingers curl in the anti-clockwise direction.

9. The relation between the direction of current and the direction of magnetic field is?
a) Same direction
b) Opposite direction
c) Perpendicular
d) Unrelated
View Answer

Answer: c
Explanation: When a conductor carries a certain value of current, the force developed in the conductor, the current in the conductor and the magnetic field in the conductor are mutually perpendicular to each other.
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Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.

To practice all areas of Basic Electrical Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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