(a) The cylinders A-D shown below are all made from copper. Rank them in order of increasing resistance. Cylinders A, B, and C have the same length. Cylinders B and D have the same diameter. A с D (b) Cylinder D has a diameter of 0.56 mm and a length of 3 mm. Calculate the resistance of cylinder D. The resistivity of copper is 1.68 x 10-8 N-m. (answer: 2.0 x 10-4 (2) (c) If the length of each cylinder is doubled and the diameter of each cylinder is doubled, by what factor does the resistance of each cylinder change? (answer: decreases by a factor of 2) (d) If the length of each cylinder in halved and the diameter of each cylinder is halved, by what factor does the resistance of each cylinder change? (answer: increases by a factor of 2) (4) The resistivity of copper is 1.68 x 10-8 -m. The resistance per unit length (R/L) of a certain copper cable is 1.61 x 10-5 N/m. (a) What is the cross-sectional area of the cable? (answer: 1.04 x 10-³ m²] (b) The above cable is used to transmit electricity from a power station to an electrical substation 42.8 km distant. If the voltage at the substation is 2480 V, what is the required voltage at the power station when the current running through the cable is 856 A? (answer: 3070 V) (b) What is the total heat energy deposited (in Joules) in the wire in 1 hour? (answer: 1.82 x 10⁹ J)

The resistance of a coil of copper wire is 4 Ω at 5 °C . What is the resistance at 55 °C .The coefficient of resistivity for copper is 4.3 × 10−3°C−.

Consider the following. R Vba = 12 V (a) Find the current through the resistor in the figure above. (Take R = 6 02.) (b) If the resistor is made of carbon, what will its resistance be when its temperature is increased by 97.0 C°? (The temperature coefficient of resistivity for carbon is -5.0 x 10-4 (°C)-¹.) b

(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.