Q7.(Page No.369, 18.9 Exercises, Problem No.3) The resistivity of a sample of germanium is 6.0 x 102 m. A cylinder of germanium 5.0 mm long and 0.50 mm in radius has a p.d. of 10 V applied across its ends. (a) What current passes through the specimen? (b) What is the current density (1/A) in the sample?

A conductor has a cross-sectional area of 2.3x 10P m and the number of free electrons per unit volume is 8.5x 1028 electron/m³. When the current is 6.1 A, find the drift speed (in mm/s) of the electrons. Use the charge of the electron to be 1.6x1019 C. Select one: OA 0.26 OB. 25.60 OC.0.13 OD. 19.50 OE 0.20

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.

Question 1. A 34.5 m length of copper wire at 20.0°C has a radius of 0.25 mm. If a potential difference of 9.0 V is applied across the length of the wire, determine (a) the current in the wire. (b) If the wire is heated to 30.0°C while the 9.0 V potential difference is maintained, what is the resulting current in the wire?

Copper is used in all household wiring. However, Aluminum, being much cheaper, is used in power distribution over large distances. The resistivity of Cu wire is 1.68x10-8 m and the resistivity of Aluminum wire is 2.65x108 2m. A typical power line might be 4.6 cm in diameter. Power lines transmit power at very high voltages so that relativley small current can be used. What is the power loss in a single line of Aluminum carrying a current of 140 A through a distance of 220 km? Number W. What is the power loss in a single line of Copper carrying a current of 140 A through a distance of 220 km? Number W. If the average cost of electricity in Ontario is $0.125 per kWh, the cost of copper is 12.6 dollars /kg, and the cost of Aluminum is 4 dollars/kg, how much time of continuous power transmission is required/(km of line) before the cost savings during use balances the extra cost of using copper. The density of Aluminum is 2700kg/m³ and the density of copper is 8960 kg/m³. Number years.