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प्रश्न
How does the magnetic effect of electric current help in the working of an electric bell? Explain with the help of a diagram.
उत्तर
The doorbell or the electric bell makes use of the principle of an electromagnet. A horseshoe type of electromagnet is used in an electric bell which is connected to the source of current through a switch. It has a metallic gong, a hammer to strike the gong, and a screw attached to a soft iron strip.
When the button is pressed, the circuit is complete, and the hammer gets attracted to the gong thereby striking it to produce a ringing sound.
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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.
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Write the correct option by observing the figures.
In the Activity shown below, how do we think the displacement of rod AB will be affected if
- current in rod AB is increased
- a stronger horse-shoe magnet is used
- length of the rod AB is increased?
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(b) State whether the following statements are true or false:
(i) Magnetic poles exist in pairs.
(ii) Global warming is a desirable aspect of the intensified greenhouse effect.
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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?
As shown in the diagram an aluminium rod 'AB' is suspended horizontally between the two poles of a strong horse shoe magnet in such a way that the axis of rod is horizontal and the direction of the magnetic field is vertically upward. The rod is connected in series with a battery and a key.
State giving reason:
- What is observed when a current is passed through the aluminium rod from end B to end A?
- What change is observed in a situation in which the axis of the rod 'AB' is moved and aligned parallel to the magnetic field and current is passed in the rod in the same direction?
