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प्रश्न
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 ______.
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उत्तर
D.C. motor core- soft iron, magnet - steel
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संबंधित प्रश्न
A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm s−1 in a direction normal to the
- longer side,
- shorter side of the loop?
For how long does the induced voltage last in each case?
A line charge λ per unit length is lodged uniformly onto the rim of a wheel of mass M and radius R. The wheel has light non-conducting spokes and is free to rotate without friction about its axis (Figure). A uniform magnetic field extends over a circular region within the rim. It is given by,
B = − B0 k (r ≤ a; a < R)
= 0 (otherwise)
What is the angular velocity of the wheel after the field is suddenly switched off?
Explain why, an electromagnet is called a temporary magnet.
When current is 'switched on' and 'switched off' in a coil, a current is induced in another coil kept near it. What is this phenomenon known as?
What do you understand by the term "electromagnetic induction"? Explain with the help of a diagram.
How is the working of an electric bell affected, if alternating current be used instead of direct current?
In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .
A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.
A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .
Write Fleming’s right hand thumb rule with the help of diagram.
