Q4 of 41 Page 209

Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal ?

The coils (or heating elements) of toasters and electric irons are made of an alloy rather than a pure metal due to the following two reasons:

1) The resistivity of an alloy is much higher than that of a pure metal, and


2) An alloy does not undergo oxidation easily even at high temperature


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2

Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

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Let the resistance of an electrical component remain constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?

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Use the data in Table on page 23 of this book to answer the following:

(a) Which among iron and mercury is a better conduction?


(b) Which material is the best conductor?

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Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 resistor, an 8 resistor, and a 12resistor, and a plug key, all connected in series.