Chapter 26 Flashcards
(10 cards)
Consider positive and negative charges of equal magnitude moving horizontally through the four regions shown in the figure. Rank the current in these four regions from highest to lowest
a>b=c>d
A cylindrical wire has a radius r and length ℓ. If both rand ℓ are doubled, does the resistance of the wire
(a) increase,
(b) decrease, or
(c) remain the same?
b
In the figure (quadratic curve), as the applied voltage increases, does the resistance of the diode
(a) increase,
(b) decrease, or
(c) remain the same
b
When does an incandescent lightbulb carry morecurrent,
(a) immediately after it is turned on and the glow of themetal filament is increasing or
(b) after it has been on for a few milliseconds and theglow is steady?
a
Two wires A and B with circular cross sections are made of the same metal and have equal lengths, but the resistance of wire A is three times greater than that of wire B. What is the ratio of the cross-sectional area of A to that of B?
1. 3
2. √3
3. 1
4. 1/√3
5. 1/3
5
A cylindrical metal wire at room temperature is carrying electric current between its ends. One end is at potential VA = 50 V, and the other end is atpotential VB = 0 V. Rank the following actions in terms of the change thateach one separately would produce in the current from the greatest increaseto the greatest decrease. In your ranking, note any cases of equality.
(a) Make VA = 150 V with VB = 0 V.
(b) Adjust VA to triple the power with which the wire converts electrically transmitted energy into internal energy.
(c) Double the radius of the wire.
(d) Double the length of the wire.
(e) Double the Celsius temperature of the wire
- b > c > a > e > d
- d > a > c > b > e
- c > a > b> e > d
- a > c > d > e > b
- None of these.
3
A potential difference of 1.00 V is maintained acrossa 10.0-Ω resistor for a period of 20.0 s. What totalcharge passes by a point in one of the wiresconnected to the resistor in this time interval?
2C
Three wires are made of copper having circular crosssections. Wire 1 has a length L and radius r. Wire 2has a length L and radius 2r. Wire 3 has a length 2Land radius 3r. Which wire has the smallestresistance?
3
Two lightbulbs both operate on 120 V. One has apower of 25 W and the other 100 W. Which lightbulbhas higher resistance?
1. The dim 25-W lightbulb does.
2. The bright 100-W lightbulb does.
3. Both are the same.
1
Two lightbulbs both operate on 120 V. One has apower of 25 W and the other 100 W. Which lightbulbcarries more current?
1. The dim 25-W lightbulb does.
2. The bright 100-W lightbulb does.
3. Both are same
2
