2. Page > of 3 5. Two long coaxial metal cylinders with radii a and b are separated by material of conductivity o (see figure below). The conductivity is not uniform and changes as = (s)0 where k is a constant. If the two cylinders are kept at a potential difference V, find the resistance R between the cylinders. (s)o Hint: Since the conductivity is a function of position, the charge density in the resistive medium is not zero and E does not go like 1/s. However, since the current I is steady, the same current flows across each eylindrical surface. Instead of using Gauss' Law, find E in terms of I, from Ohm's Law. acer F10 F11

(a) What is the resistivity of the wire? (b) What material is the wire made of? You will have to look up the various resistivities.

To what value would you have to raise the temperature of a copper wire (originally at 20 °C) to increase its resistance by 18 % ? Assume the temperature coefficient of resistivity of copper is 0.0039 (°C) 1. Express your answer using two significant figures. ? Tinal = °C Submit Request Answer

Question A2 Pure copper has a resistivity of 1.68 x 10-8 Nm. Some accurate cubes of copper are prepared, and electrical measurements are made, for which current is passed across a pair of opposite faces. a) Comparing a 2.5 cm cube and a 5 cm cube, which will have the higher conductance? Ex- plain your answer. b) Given eight 1 cm cubes, how can they be stacked to get the highest and the lowest resis- tance between opposite faces of the stack? Calculate the resistance of each stack.

are made of the same metal. 7) wires 1 and 2 wire 2 has twice the length and twice the diameter of wire 1. What are the ratios (a) Q₂/Q² of the resistivities and (b) R.2/121 of the resistance of the two wires? A) P₁/P₁ = 1, 1₂/1²₁=0.5 13) P₂/p₁ = 1, 82₂/124₁ =0.25 C) P₁/P₁ = 0.5² h₂/1²₁=0.5 D) P₁/P₁ = 0.25, 1₂₁/1²₁=0.5 2 र

Problem 2: The battery has a potential difference of 10 V and each resistor has a resistance of 2 ohms. RI R2 'R3 (a) Determine the equivalent resistance of the 3 resistors. (i.e. if you replace the three resistors shown with a single equivalent resistor, what value should you select?) 3 ohms (b) Determine the current through each resistor. (R1 has 1.66 A, R2 has 1.66 A, R3 has 3.33A)

Wire B has twice the length and twice the radius of wire A. Both wires are made from the same material. If wire A has a resistance R, what is the resistance of wire B?

QUESTION 1 Consider a carbon rod resistor that has a uniform cross-sectional area of 5.00 mm-. When a potential difference of 3.5 V is applied across the ends of the rod, the rod carries a current of 0.40 A. Find the rod's length (in cm) if its resistivity is p=3.5 x 10 5 Q. m.