What is permanent magnet and electromagnet?

What is permanent magnet and electromagnet?
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Permanent magnet: A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. As the name suggests, a permanent magnet is 'permanent'. This means that it always has a magnetic field and will display a magnetic behavior at all times. 


Electromagnet: An electromagnet is an object having a coil of wire wrapped around a core of ferromagnetic material like steel, which acts as a magnet when an electric current passes through the coil. If the current is interrupted, the magnetism is lost.

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What happens when you reverse the direction of the current in an electromagnet?

Description : What happens when you reverse the direction of the current in an electromagnet?

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Description : A permanent magnet stepper motor with 8 poles in stator and 6 poles in rotor will have a step angle of (a) 7.5° (b) 15° (c) 30° (d) 60°

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Is the idea of permanent magnet "free energy" generators impossible?

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Last Answer : answer:It's hard to say. I've tried building a few myself with no avail. I have gotten close a few times though, and that's just tinkering around. The problem with permanent magnets in a ... com/watch?v=bssBAb6EzM4&feature=related This one looks like it works, but was later revealed to be a hoax.

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Description : What does a permanent magnet repel? -Do You Know?

Last Answer : answer:

Which of the following iron and steel is used to make a permanent magnet ?

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Last Answer : The most durable strong magnet is nickel.

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Description : What is a permanent magnet ?

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Description : When a piece of iron rod is brought near a permanent magnet for a while it becomes magnitised by?

Last Answer : Need answer

What does a permanent magnet repel?

Description : What does a permanent magnet repel?

Last Answer : – Diamagnetic substances only

Permanent magnet is normally made of- (a) Aluminum (b) Wrought iron (c) Cast iron (d) Alnico alloys

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Last Answer : Ans: C

Which of the following electric meter movements uses a stationary permanent magnet and movable coil? A. D'Arsonval B. Electrodynamometer C. Moving iron-vane D. Inclined coil iron-vane

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The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction

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What is the device, which depends on the action of a movalbe permanent magnet, in aligning itself in the resultant field produced by a fixed permanent magnet or current- carrying coils whose axes are displaced by a fixed angle?

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In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field

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The coating on the plastic tape you use in your cassette players is w) diamagnetic x) paramagnetic y) ferromagnetic z) a permanent magnet

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Permanent Magnet Moving Coil (PMMC) Instrument

Description : Permanent Magnet Moving Coil (PMMC) Instrument

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A permanent magnet moving coil instrument gives full scale deflection of 25mA when a voltage of 75mV is applied across it. Calculate: (i) Resistance of shunt required for full scale deflection of 150 A. (ii) Series resistance for full scale deflection of 500 V.

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Last Answer : Answer :

(i) Explain the working principle of Electrostatic and permanent magnet speaker. (ii) Compare Woofer and Tweeter.

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A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD)

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The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from

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The following motor definitely has a permanent magnet rotor

Description : The following motor definitely has a permanent magnet rotor  (A) DC commutator motor (B) Brushless dc motor (C) Stepper motor (D) Reluctance motor

Last Answer : The following motor definitely has a permanent magnet rotor Stepper motor

The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : -

Description :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

Last Answer :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

A permanent magnet

Last Answer : A permanent magnet attracts some substances and repels others.

The working of a meter is based on the use of a permanent magnet...

Description : The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields

Last Answer : The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields a soft iron shielding is used.

Preferred material for permanent magnet is:

Last Answer : Preferred material for permanent magnet is: Alnico