Quizbank/Electricity and Magnetism (calculus based)/QBCh9

QB153086031104

QB:Ch 9:V1
QB153086031104 1) Calculate the resistance of a 12-gauge copper wire that is 19 m long and carries a current of 59 mA. The resistivity of copper is 1.680E-08 &Omega;&middot;m and 12-gauge wire as a cross-sectional area of 3.31 mm2.
 * a) 7.970E-02 &Omega;
 * b) 8.767E-02 &Omega;
 * c) 9.644E-02 &Omega;
 * d) 1.061E-01 &Omega;
 * e) 1.167E-01 &Omega;

2) A device requires consumes 81 W of power and requires 2.34 A of current which is supplied by a single core 10-guage (2.588 mm diameter) wire. Find the magnitude of the average current density.
 * a) 3.342E+05 A/m2
 * b) 3.677E+05 A/m2
 * c) 4.044E+05 A/m2
 * d) 4.449E+05 A/m2
 * e) 4.894E+05 A/m2

3) Imagine a substance could be made into a very hot filament. Suppose the resitance is 1.95 &Omega; at a temperature of 96&deg;C and that the temperature coefficient of expansion is 4.400E-03 (&deg;C)&minus;1). What is the resistance at a temperature of 469 &deg;C?
 * a) 4.449E+00 &Omega;
 * b) 4.672E+00 &Omega;
 * c) 4.905E+00 &Omega;
 * d) 5.150E+00 &Omega;
 * e) 5.408E+00 &Omega;