Classes

Change the way you learn with Maqsad's classes. Local examples, engaging animations, and instant video solutions keep you on your toes and make learning fun like never before!

Class 9Class 10First YearSecond Year
##### 13.4 A rectangular bar of iron is 2.0 \mathrm{~cm} by 2.0 \mathrm{~cm} in cross section and 40 \mathrm{~cm} long. Calculate its resistance if the resistivity of iron is 11 \times 10^{-3} \Omega \mathrm{m} .(Ans: 1.1 \times 10^{-4} \Omega )

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?