An electric toaster element Nichrome is 20 How
- Slides: 8
An electric toaster element (Nichrome) is 20. How great is the current when it is connected to a 120 v line? (1)1/6 A (4) 6 A (2) 1 A (5) 120 A (3) 5 A (6) 240 A 0. 8 A runs through a lamp when attached to a 32 v source. What is its resistance? (1) 0. 025 (2) 25. 6 (3) 32 (4) 40
The resistance of a 10, 000 ft (3, 048 m) long power line must not exceed 4. What is the smallest size copper wire that can be used for this line? 4 l /A = (1. 70 10 -8 m)(3048 m)/A A 1. 2954 10 -8 m 2 r 2 1. 2954 10 -8 m 2 r 2. 03 10 -3 m d 4. 06 mm Gauge 6 wire or smaller
Two wires, A and B, are made of the same metal and have equal length, but the resistance of wire A is four times the resistance of wire B. How do their diameters compare? 1) The diameter of wire A is four times that of wire B 2) The diameter of wire A is twice that of wire B 3) The diameter of wire A is equal to that of wire B 4) The diameter of wire A is one half of that of wire B 5) The diameter of wire A is one quarter of that of wire B
A wire of resistance R is stretched uniformly (keeping its volume constant) until it is twice its original length. What happens to the resistance? 1) it increases by a factor 4 2) it increases by a factor 2 3) it stays the same 4) it decreases by a factor 2 5) it decreases by a factor 4 For a cylinder: Volume = area length
If an electric iron draws 5 Amperes from a 120 v line, at what rate is it using power? (1)6 Watts (4) 240 Watts (2) 12 Watts (5) 600 Watts (3) 120 Watts (6) 720 Watts
Which has a greater resistance, a 100 Watt lightbulb or a 25 Watt lightbulb? 1) the 25 W bulb 2) the 100 W bulb 3) the same for both Which carries the greater current? 1) the 25 W bulb 2) the 100 W bulb 3) the same for both
A 1440 W appliance is designed to operate using a 120 V power source. What is the resistance of the oven? 1) 0. 1 2) 10 3) 72 4) need to know the current 5) none of these
Answers to the multiple choice questions (4) 6 A (4) 40 (4) The diameter of wire A is one half of that of wire B half the diameter means one quarter the cross sectional area 5) it decreases by a factor 4 Doubling the length alone doubles the resistance, but simultaneously the cross sectional area is halved as well…another doubling! (5) 600 Watts 1) the 25 W bulb 2) the 100 W bulb 2) 10
