current-electricity Question 5
Question: Q. 2. Define temperature coefficient of resistivity.
R [SQP 2018-19]
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Solution:
Ans. Fractional change in resistivity per unit change in temperature.
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[CBSE Marking Scheme 2018-19]
AI Q. 3. Nichrome and copper wires of same length and same radius are connected in series. Current $I$ is passed through them. Which wire gets heated up more? Justify your answer. R [O.D. I, II, III 2017]
Ans. (i) Nichrome $1 / 2$
(ii) $\mathrm{R}{N i}>\mathrm{R}{\mathrm{Cu}}$ (or Resistivity Ri ${\mathrm{Ni}}>$ Resistivity ${\mathrm{Cu}}$ ) Justification : Conduction of electrons
[CBSE Marking Scheme 2017]
Detailed Answer :
Two wires having similar length and radius, Nichrome wire gets heated up more as compared to copper wire since resistivity of Nichrome is more than that of Copper.
[AI Q. 4. Plot a graph showing the variation of current $I$ versus resistance $R$, connected to a cell of emf $E$ and internal resistance $r$. $U$ [CBSE SQP 2017-18]
Ans.
$$ I=\frac{E}{r+R} $$
[CBSE Marking Scheme 2017]
