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प्रश्न
The magnetic effect of current was discovered by:
(a) Maxwell
(b) Fleming
(c) Oersted
(d) Faraday
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उत्तर
Oersted
Oersted first discovered that current-carrying wire produces magnetic field around it.
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संबंधित प्रश्न
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
An electric bell has an electromagnet.
Which effect of current can be utilised in detecting a current carrying wire concealed in a wall?
For the coil in the diagram below, when the switch is pressed:
(a) what is the polarity of end A?
(b) which way will the compass point then?
What device reverses the current?
Which way does the wire in the diagram below tend to move?
The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a galvanometer. The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was ______.
How should the electric lamps in a building be connected so that the switching on or off in a room has no effect on other lamps in the same building?
Observe the following diagram and choose the correct alternative:
(ii) Global warming is a desirable aspect of the intensified greenhouse effect.
A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with a reason.
Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give reason.
______ are also used to remove splinters of steel or iron in hospitals dealing with eye injuries.
______ cells cannot be recharged after use.
What do you mean by the magnetic effect?
The figure given below shows the magnetic field around the conductor. Study it and answer the questions:
- What changes are caused by increasing current?
- What do you see when the magnetic needle is kept a little away from the wire?
- In the second part of the figure, the iron filings arrange themselves in a circular manner around the wire. Why does this happen?
A student was asked to perform an experiment to study the force on a current carrying conductor in a magnetic field. He took a small aluminium rod AB, a strong horse shoe magnet, some connecting wires, a battery and a switch and connected them as shown. He observed that on passing current, the rod gets displaced. On reversing the direction of current, the direction of displacement also gets reversed. On the basis of your understanding of this phenomenon, answer the following questions:
- Why does the rod get displaced on passing current through it?
- State the rule that determines the direction of the force on the conductor AB.
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- If the U-shaped magnet is held vertically and the aluminium rod is suspended horizontally with its end B towards due north, then on passing current through the rod from B to A as shown, in which direction will the rod be displaced?
- Name any two devices that use current carrying conductors and magnetic fields.
OR
Draw the pattern of magnetic field lines produced around a current carrying straight conductor held vertically on a horizontal cardboard. Indicate the direction of the field lines as well as the direction of current flowing through the conductor.
Make four electromagnets with 20, 40, 60 and 80 turns. Connect them one by one to a battery of 2 cells. Bring the electromagnet near a box of pins. Count the number of pins attracted by it. Compare the strengths of the electromagnets.
