Please Note: It may not always be possible to include the necessary special characters, superscripts, subscripts, etc. in e-mail responses to this group of exercises. We suggest that you discuss this matter with your professor/class and decide upon a system for indicating such characters. You may cut/paste some characters and/or Greek letters from Microsoft Word, using the Insert menu. Alternatively, we suggest that you agree upon abbreviations for or spell out symbols, Greek letters, or characters and indicate superscripts and subscripts by using "sup", "sub", or up/down carats.

1			Jeff needs a 100-Ω resistor for a circuit, but he only has a box of 300-Ω resistors. What can he do?
2			A battery is connected to a clock by copper wires as shown in Fig. 18.44. What is the direction of current through the clock (B to C or C to B)? What is the direction of current through the battery (D to A or A to D)? Which terminal of the battery is at the higher potential (A or D)? Which side of the clock is at the higher potential (B or C)? Does current always flow from higher to lower potential? Explain. <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 18.44::/sites/dl/free/0070524076/58001/18_044.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 18.44 (8.0K)</a>Fig. 18.44
3			(a) What is the direction of the current in the vacuum tube shown in Fig. 18.48? (b) Electrons hit the anode at a rate of 6.0 × 1012 per second. What is the current in the tube? <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 18.48::/sites/dl/free/0070524076/58001/18_048.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 18.48 (10.0K)</a>Fig. 18.48
4			The current in the electron beam of a computer monitor is 320 μA. How many electrons per second hit the screen?
5			What is the energy stored in a small battery if it can move 675 C through a potential difference of 1.20 V?
6			83 mA of current flow through the resistor of Fig. 18.49. (a) What is the resistance of the resistor? (b) In what direction does the current flow through the resistor? <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 18.49::/sites/dl/free/0070524076/58001/18_049.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 18.49 (2.0K)</a>Fig. 18.49
7			A diode is a semiconductor device that allows current to flow easily in one direction but not in the other. When 60.0 mA of current flows in the preferred ("forward biased") direction, the potential difference across the diode is 1.0 V. If a 1.0-V potential difference is applied to the diode in the opposite direction ("reverse biased"), the current is 0.020 mA. Calculate the resistance of the diode in each case.
8			(a) What are the ratios of the resistances of (a) silver and (b) aluminum wire to the resistance of copper wire (RAg/RCu and RAl/RCu) for wires of the same length and the same diameter? (c) Which material is the best conductor, for wires of equal length and diameter?
9			Find the equivalent capacitance between points A and B for the three capacitors in parallel in Fig. 18.54. <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 18.54::/sites/dl/free/0070524076/58001/18_054.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 18.54 (2.0K)</a>Fig. 18.54
10			What is the power dissipated by the resistor in the circuit of Fig. 18.69? <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 18.69::/sites/dl/free/0070524076/58001/18_069.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 18.69 (2.0K)</a>Fig. 18.69
11			What is the current in a 60.0-W bulb when connected to a 120-V emf?
12			A person bumps into a set of batteries with an emf of 100.0 V that can supply a maximum power of 5.0 W. If the man's resistance between the points where he contacts the batteries is 1.0 kΩ, how much current passes through him?