Q6 of 11 Page 44

The resistance of a conductor of length x is r. If its area of cross section is a, what is its resistivity? What is its unit?

We know that Resistivity ρ = RA/L


where R = Resistance of the conductor


A = Cross sectional area of the conductor


L = Length of the conductor


Here A = a and L = x


Therefore, Resistivity ρ = Ra/x


It's units are ohm.m2/m = Ωm


More from this chapter

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4

The following table shows current in Amperes and potential difference in Volts.

A. Find the average resistance.


B. What will be the nature of the graph between the current and potential difference? (Do not draw a graph.)


C. Which law will the graph prove?


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Match the pairs

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Resistances and are connected as shown in the figure. S1 and S2 are two keys. Discuss the current flowing in the circuit in the following cases.


A. Both and are closed.


B. Both and are open.


C. is closed but is open

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Three resistances x1, x2 and x3 are connected in a circuit in different ways. X is the effective resistance. The properties observed for these different ways of connecting x1, x2 and x3 are given below. Write the way in which they are connected in each case. (I-current, V-potential difference, x-effective resistance)

A. Current I-flows through and


B. x is larger than and


C. x is smaller than and


D. The potential across and is the same


E.


F.