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प्रश्न
What is an electromagnet?
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
How will you make an iron bar electromagnet? Draw a diagram showing the polarities of the electromagnet?
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?
Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the electromagnet.
What is an electric motor?
Name the type of transformer shown in fig . What changes will you observe regarding the brightness of the lamp, if
(a) The no. of turns in the secondary is doubled?
(b) The part X of the transformer is removed?
( c) The core of the transformer is made out of copper?
(d ) The A.C. supply is replaced by D.C.?
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.
Describe a simple Experiment to demonstrate that there Exists a magnetic field around a current-carrying conductor.
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
What will be the effect on the working of an electric bell if instead of a direct current an alternating current is used?
State the factors that can increase the speed of rotation of the coil in a D.C. motor.
State the principle of 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 and the coil is minimum.
State important properties (or characteristics) of magnetic lines of force around a straight conductor.
A current-carrying solenoid is suspended so as to freely rotate in a horizontal plane. State in what direction will it rest. Give a reason for your answer.
or
When a solenoid that is carrying current is freely suspended, it comes to rest in a particular direction. Why does this happen?
What are the factors that govern the magnitude of force acting on a current carrying conductor which is freely suspended in a magnetic field?
State and explain Maxwell’s Cork Screw Rule.
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
Which magnet will you use?
Iron is to be separated from trash.
