Narendra Kumar Solutions for Chapter: Electricity, Exercise 8: HIGHER ORDER THINKING SKILLS (HOTS)

A TV set picture tube shoots out a beam of electrons. The current due to this beam is $10 \mathrm{mA}$. How many electrons will strike the TV screen every second?

A cylindrical wire is stretched to increases its length by $10\%$. Calculate the percentage increase in resistance.

Two students perform the experiments on series and parallel combinations of two given resistors $R_1$ and $R_2$ and plot the following $V-I$ graphs.

Which of the graphs is (are) correctly labelled in terms of the words 'series' and parallel justify your answer.

$V-I$ graph for two resistors is given below. Which of the two has minimum resistance?

The electrical resistivity of few materials is given below in ohm-metre. Which of these materials can be used for making element of a heating device?

Two metallic wires $A$ and $B$ are connected in parallel. Wire $A$ has length $l$ and radius $r$, wire $B$ has a length $2 l$ and radius $2 r$. Compute the ratio of the total resistance of parallel combination and the resistance of wire $A$.

The electric power consumed by a device may be calculated by using either of the two expressions $P=I^{2}R$ or $P=\frac{V^2}{R}$. The first expression indicates that it is directly proportional to $R$ whereas the second expression indicates inverse proportionality. How can the seemingly different dependence of $P$ or $R$ in these expressions explained.

A parallel combination of three resistance take a current of $7.5 \mathrm{A}$ from a $30 \mathrm{V}$ battery. If two of the resistance values are $10 \mathrm{\Omega }$ and $12 \mathrm{\Omega }$ find the third.