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Why does the cord of an electric heater ...

Why does the cord of an electric heater not glow while the heating element does ?

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The heating element of an electric heater is made of an alloy (such as nichrome) which has high resistance whereas the cord is made of copper metal which has very, vert low resistance. Now, the heating element of an electric heater made of nichrome glows because it becomes red-hot due to the large amount of heat produced on passing current (because of its high resistance). On the other hand, the connecting cord of the electric heater made of copper does not glow because negligible heat is produced in it by passing the same current (due to its extremely low resistance).
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(a) What is meant by saying that the potential difference two points is 1 volt ? Name a device that helps to measure the potential difference across a conductor. (b) Why does the connecting cord of an electric heater not glow hot while the heating element does ? ( c) Electrical resistivities of some substances at 20^@ C are given below : Silver 1.60 xx 10^-8 Omega m Copper 1.62 xx 10^-8 Omega m Tungsten 5.20 xx 10^-8 Omega m Iron 10.0 xx 10^-8 Omega m Mercury 94.0 xx 10^-8 Omega m Nichrome 100 xx 10^-6 Omega m . Answer the following question in relation to them : (i) Among silver and copper, which one is a better conductor ? Why ? (ii) Which material would you advise to be used in electrical heating devices ? Why ?

Element of an electric heater is made of which of the following metals ?

(a) what is menat by the heating effect of current ? State three factors on which the heat produced in a wire by an electric current depends. (b) Explain why, through the heating element of an electric heater glows, but its connecting cord does not l glow. ( c) An electric geyser of resistance 20 Omega takes a current of 5 A. calculate the heat produced in 2 minutes. (d) Name the commercial unit of electric energy. How many joules are equal to this unit ?

Why does zinc oxide exhibit enhanced electrical conducity on heating ?

LAKHMIR SINGH & MANJIT KAUR-ELECTRICITY -Exercise
  1. How can three resistors of resistances 2 Omega,3 Omega, and 6 Omega be...

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  2. What is : (a) the highest (b) the lowest total resistances that can b...

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  3. Why does the cord of an electric heater not glow while the heating ele...

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  4. Compute the heat generated while transferring 96000 coulombs of charge...

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  5. An electric iron of resistance 20 Omega takes a current of 5 A. Calcul...

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  6. What determines the rate at which energy is delivered by a current ?

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  7. An electric motor takes 5 A from a 220 V line. Determine the power and...

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  8. A piece of wire of resistance R is cut into five equal parts. These pa...

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  9. Which of the following terms does not represent electrical power in a ...

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  10. An electric bulb is rated 220 V and 100 W. When it is operated on 110 ...

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  11. Two conducting wires of the same material and of equal length and equa...

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  12. How is voltmeter connected in the circuit to measure potential differe...

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  13. A copper wire has a diameter of 0.5 mm and a resistivity of 1.6 xx 10^...

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  14. The value of current, I, flowing in a given resistor for the correspon...

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  15. When a 12 V battery is connected across an unknown resistor, there is ...

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  16. A battery of 9 V is connected in series with resistors of 0.2 Omega, 0...

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  17. How many 176 Omega resistors (in parallel) are required to carry 5 A ...

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  18. Show how you would connect three resistors, each of resistance 6 Omega...

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  19. Several electric bulbs designed to be used on a 220 V electric supply ...

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  20. A hot plate of an electric oven connected to a 220 V lines has two res...

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