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प्रश्न
What is an electromagnet?
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उत्तर
An electromagnet is a temporary strong magnet made from a piece of soft iron when current flows in the coil wound around it. It is an artificial magnet.
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संबंधित प्रश्न
State two ways of magnetising an iron piece?
Suppose you are given a long bar magnet and you are asked to break it into four small magnets. Draw diagrams showing the polarities of each broken part.
Tick the most appropriate answer.
Which of the following methods is used to magnetize a magnetic without touching it by a magnet?
Name two factors on which the strength of magnetic field of an electromagnet depends and state how does it depend on the factors stated by you.
State three uses of an electromagnet?
What is an electric motor?
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
Electric bell ______.
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
Electromagnet ______.
Complete the following sentence :
On reserving the direction of current in a wire, the magnetic field produced by it gets _____.
The magnetic flux through a coil having 100 turns decreases from 5 milli weber to zero in 5 second. Calculate the e.m.f. induced in the coil.
State the two properties of the magnetic lines of force around a circular coil.
State the purpose of the iron core.
State the condition when an electric charge can give rise to a magnetic field.
State the factors that can increase the speed of rotation of the coil in a D.C. motor.
State the energy change that takes’place in a D. C. motor.
State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting an the coil is maximum.
The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
Write the answer in your word.
How is an electromagnet made?
