Post on 19-Dec-2015
Currents
11/17/08
Fig P27-8, p.852
Fig 27-5, p.836
Fig 27-9b, p.841
Hig
h P
oten
tial
Low
Pot
entia
l
dx
dVA
dt
dq
Table 27-1, p.837
Fig 27-3, p.834
Fig 27-9b, p.841
Fig 27-13, p.845
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.
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 = VI and the 30 W bulb must have the higher resistance because V = IR.
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.
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.
Ia = Ib Ic = Id Ie = If
Ia > Ic > Ie
Problems
1. Suppose that you have 2.10 108 doubly charged positive ions per cubic centimeter all moving in the same direction with a speed 1.4 105 m/s, Can the total current be calculated?
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?