1. Currents 11/17/08

2. Fig P27-8, p.852

3. Fig 27-5, p.836

4. Fig 27-9b, p.841 High Potential Low Potential

5. Table 27-1, p.837

6. Fig 27-3, p.834

7. Fig 27-9b, p.841

8. Fig 27-13, p.845

9. Fig 27-13, p.847 The same potential difference is applied to the two light bulbs shown in the figure. Which one of the following statements is true? a. The 30 W bulb carries the greater current and has the higher resistance. b. The 30 W bulb carries the greater current, but the 60 W bulb has the higher resistance. c. The 30 W bulb has the higher resistance, but the 60 W bulb carries the greater current. d. The 60 W bulb carries the greater current and has the higher resistance.

10. Fig 27-13, p.847 The same potential difference is applied to the two light bulbs shown in the figure. Which one of the following statements is true? c.The 30 W bulb has the higher resistance, but the 60 W bulb carries the greater current. This is true because the potential difference is the same across the two bulbs so the 60 W bulb must have the higher current because P =  V  I and the 30 W bulb must have the higher resistance because  V = I  R.

11. Fig 27-15, p.847 For the two lightbulbs shown in the figure rank the current values at points a through f from the greatest to the lowest.

12. Fig 27-15, p.847 For the two lightbulbs shown in the figure rank the current values at points a through f from the greatest to the lowest. I a = I b I c = I d I e = I f I a > I c > I e

13. Problems 1.Suppose that you have 2.10  10 8 doubly charged positive ions per cubic centimeter all moving in the same direction with a speed 1.4  10 5 m/s, Can the total current be calculated?

14. Problems 5.It takes about 50 mV of current to electrocute a person if the current passes near the heart. If an electrician’s resistance is 1800 , what would be a fatal voltage?