Explain the following.
(a) Copper and aluminium wires are usually employed for electricity
transmission. Explain the reason.
(b) Explain how does the resistance of a wire vary with its length.
(c) The tungsten is used almost exclusively for filament of electric lamp.
Comment.
(d) Electromagnets are better than permanent magnets. Why?
(e) If the current flows through wire, does the wire behave like a
magnet?
Answers
Answer:
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Explanation:
1. Copper and aluminum are good conductors of electricity also they have low resistivity. So they are usually used for electricity transmission. They have very low resistance and allow the current to flow through them easily. Hence, they are used to make wires for electrical transmissions.
2. First, the total length of the wires will affect the amount of resistance. The longer the wire, the more resistance that there will be. More collisions mean more resistance. Second, the cross-sectional area of the wires will affect the amount of resistance.
3. The metal tungsten is almost exclusively used for the filament of the electric lamp because it has a very high melting point due to which it does not melt even when it is heated to high temperatures due to the passage of electric current.
4. Electromagnets have the main benefit of manipulating their magnetic pull strength – both by turning the magnet on or off and by adjusting the current. They also feature greater pull strength than permanent magnets. Some estimates place the largest electromagnet at 20 times stronger than the strongest permanent magnet.
5. When an electric current flows through a wire, it behaves like a magnet. A current carrying coil of an insulated wire wrapped around a piece of iron is called an electromagnet. The electromagnets are also used to separate magnetic material from the junk.