Advertisements
Advertisements
प्रश्न
The coil of a moving-coil galvanometer keeps on oscillating for a long time if it is deflected and released. If the ends of the coil are connected together, the oscillation stops at once. Explain.
Advertisements
उत्तर
When the ends of the coil are not connected, the coil acts as an inductor in which oscillations persist until the current decays slowly. When these ends are connected, the coil forms a close loop; hence, there is inductance across the ends and the coil does not behave like an inductor. Therefore, all oscillations stop at once.
APPEARS IN
संबंधित प्रश्न
Explain different ways to induce current in a coil.
The phenomenon of electromagnetic induction is
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?
Name a common device that uses electromagnets.
What is an electromagnet? Describe the construction and working of an electromagnet with the help of a labelled diagram.
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 kind of energy change takes place when a magnet is moved towards a coil having a galvanometer at its ends?
- Name the phenomenon.
Electromagnetic induction means ______.
A conducting square loop of side l and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A uniform and constant magnetic field Bexists along the perpendicular to the plane of the loop as shown in figure. The current induced in the loop is _____________ .
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.
Transformer______.
You have been provided with a solenoid AB.
(i) What is the polarity at end A?
(ii) Give one advantage of an electromagnet over a permanent magnet.
The energy stored in a 50 mH inductor carrying a current of 4 A is ______
What for an inductor is used? Give some examples.
A closely wound circular coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced in it. Calculate the number of turns in the coil.
Using Lenz’s law, predict the direction of induced current in conducting rings 1 and 2 when the current in the wire is steadily decreasing.
A generator has an e.m.f. of 440 Volt and internal resistance of 4000 hm. Its terminals are connected to a load of 4000 ohm. The voltage across the load is ______.
We can induce the current in a coil by ____________.
For making a strong electromagnet the material of the core should be ______.
