6. [-/1 Points] DETAILS SERPSE10 26.1.P.006. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The figure below represents a section of a circular conductor of nonuniform diameter carrying a current of / = 5.10 A. The radius of cross-section A, is r, = 0.310 cm. (a) What is the magnitude of the current density across A, 7 A/m2 The radius r, at A, is larger than the radius r at A,. (b) Is the current at A, larger, smaller, or the same? The current is larger. The current is smaller. The current is the same. [c) Is the current density at A, larger, smaller, or the same? The current density is larger. The current density is smaller. The current density is the same. Assume A, = 34. (d) Specify the radius at A mm (e) Specify the current at A. (f) Specify the current density at A,. A/m Need Help? Read Watch It Submit Answer 7. [-/1 Points] DETAILS SERPSE10 26.1.P.007. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The quantity of charge q (in coulombs) that has passed through a surface of area 2.05 com- varies with time according to the equation q = 6t + 6t + 6, where t is in seconds. (a) What is the instantaneous current through the surface at ( = 0.950 s? (b) What is the value of the current density? KA/m? Need Help? And Watch It Submit Answer10. [-/1 Points] DETAILS SERPSE10 26.2.OP.005. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) A lightbulb has a resistance of 275 0 when operating with a potential difference of 170 V across it. What is the current in the lightbulb (in mA)? MA (b) What If? What would be the current in the lightbulb (in mA) if it were used in Nigeria, where the potential difference across it would be 240 V? MA Need Help? Read It Watch It Submit Answer 11. [-/1 Points] DETAILS SERPSE10 26.2.P.013.MI. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Suppose you wish to fabricate a uniform wire from 1.60 g of copper. The wire is to have a resistance of R = 0.480 $2 and all the copper is to be used. (a) What must be the length of this wire? m (b) What must be the diameter of this wire? um Need Help? Read It Master It Submit Answer12. [-11 Points] DETAILS SERPSE10 26.4.0P.O15.M|. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) A 33.7m length of copper wire at 200C has a radius of 0.31 mm. It a potential difference of 8.00 \\i' is applied across the length of the wire, determine the current in the wire. (Use the values in the following table.) Material Rtaislslv'ltya (n - rn) Temperature Coefcient of Resistivity\" a [(C)'1] copper 39 x 103 Gold 2.44 x 108 3.4 x 103 Aluminum ' 2.82 x 108 l 3.9 x 103 Tungsten 5.5 x 10'8 4.5 x 10'3 Iron 5.0 x 103 Platinum 3.92 x 10'3 Lead 3.9 x 10'3 Nichromec 1.00 x 10'6 0.4 x 10'3 Carbon 3.5 x 105 0.5 x 103 Germanium 0.46 -48 x 10'3 Silicon\" 75 x10_3 Glass 101010L4 Hard rubber 911013 Sulfur 1015 Quartz (fused) | 75 x 1016 | (a) All values at 20C. All elements in this table are assumed to be free of impurities. (b) See the section "Resistance and Temperature". (c) A nickelchromium alloy commonly used in heating elements. The resistivity of Nichrome varies with composition and ranges between 1.00 x 106 and 1.50 x 106 - m. (d) The resistivity of silicon is very sensitive to purity. The value can be changed by several orders of magnitude when it is doped with other atoms. [9 A (b) If the wire is heated to 340C while the 8.00-V potential difference is maintained, what is the resulting current in the wire? A Need Help? _'_' Submit