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प्रश्न
What is a permanent magnet? Give one use of it.
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उत्तर
A permanent magnet is a magnet made from steel such that once magnetized, it does not lose its magnetism easily. Use: It is used in the galvanometer.
संबंधित प्रश्न
State three uses of an electromagnet?
Name the type of transformer shown in Fig. What changes will you observe regarding the brightness of the lamp, if
- the number of turns in the secondary is doubled? Explain.
- the part X of the transformer is removed?
- the core of the transformer is made out of copper?
- the A.C. supply is replaced by D.C.?
State two factors on which the magnitude of an induced e.m.f. in the secondary coils of a transformer depends.
State the two properties of the magnetic lines of force around a circular coil.
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
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 factors, on which depends the magnitude of the force acting on current carrying conductor, when it is kept in a magnetic field perpendicular to it.
What are the factors that govern the magnitude of force acting on a current carrying conductor which is freely suspended in a magnetic field?
(i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(ii) Name the law which helped you to find the direction of the magnetic field lines.
