Classes
Class 9Class 10First YearSecond Year
$Example 13.1 A current of 2.4 amp is nowing in a wlre. How many electrons pass a given point in the wire in one second ir the charge on an electron is 1.6 \times 10^{-19} coulomb.$

$Example: 13.6 What would be the resistance of the above bar at 500^{\circ} \mathrm{C} ?$

$13.7 Describe a circuit which will give a continuously var ying potential.$

$14.11. A resistor of resistance 5.6 \Omega is connected across a battery of 3.0 \mathrm{~V} by means of a wire of negligible resistance. A current of 0.5 A passes through the resistor.Calculate(a) Power dissipated in the resistor.(b) Total power produced by the battery.(c) Give the reason of difference between these two quantities.Ans. [(a) 1.4W(b) 1.5 \mathrm{~W} (c) some power is lost by the internal resistance of the battery]$

$13.10 Ten resistances of different value are connected in parallel. If the p.d.across one of them is 5 \mathrm{~V} . what is the p.d. across the remalning nine resistors?$

$14.4. By applying a potential difference of 10 \mathrm{~V} across a conductor a current of 1.5 A passes through it. How much energy would be obtained from the current in 2 minutes?Ans. (1800 J)$

$13.6 When a metal object is heated. both its dimensions and fts resistlvity increase. Is the increase in resistivity likely to be a consequence of the increase in length?$