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प्रश्न
Write some of the important uses of electromagnets.
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उत्तर
- Electromagnets are used by doctors in MRI scanners.
- It is used for treating knee pain by using pulsing electromagnetic fields (PEMF).
- It is used in magnetic levitation trains.
संबंधित प्रश्न
It is desired to measure the magnitude of field between the poles of a powerful loud speaker magnet. A small flat search coil of area 2 cm2 with 25 closely wound turns, is positioned normal to the field direction, and then quickly snatched out of the field region. Equivalently, one can give it a quick 90° turn to bring its plane parallel to the field direction. The total charge flown in the coil (measured by a ballistic galvanometer connected to coil) is 7.5 mC. The combined resistance of the coil and the galvanometer is 0.50 Ω. Estimate the field strength of magnet.
When a wire is moved up and down in a magnetic field, a current is induced in the wire. What is this phenomenon known as?
Welders wear special glass goggles while working. Why? Explain.
Figure shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?
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.
D.C. motor ______.
Draw a labelled diagram to show how an electromagnet is made.
State the condition at which we say the two coils kept close to each other are perfectly coupled with each other.
Fleming's left hand rule : electric current : : Fleming's right hand rule : _______
Write the two names in the following diagram.
Right hand thumb rule.
Induced current flows through a coil ______.
