Please fully answer and show work for the three problems below. I will rate 5 st
ID: 2120045 • Letter: P
Question
Please fully answer and show work for the three problems below. I will rate 5 starts for only complete work!
1. A fuse in an electric curcuit is a wire that is designed to melt, and therby open the circut if the current exceeds a predetermined value. Suppose that the material to be used in a fuse melts when the current density rises to 440 A/cm^2. What diameter of cylindrical wire should be used to make a fuse that will limit the current to 0.50A?
2. A wire of Nichrome (a nickel-chromium-iron alloy commonly used in heating elements) is 1.0m long and 1.0mm^2 in cross-sectional area. It carries a current of 4.0A when a 2.0V potential difference is applied between its ends. Calculate the conductivity
%u03C3 of Nichrome.
3. An unknown resistor is connected between the terminals of a 3.00V battery. Energy is dissipated in the resistor at the rate of 0.540W. The same resistor is then connected between the terminals of a 1.50V battery. At what rate is energy now dissipated?
Explanation / Answer
1. for 440A area should be 1cm^2 so for 0.5 A area of the conductor = (1/400) x 0.5 cm^2 = 1/800 cm^2 => pi x r^2 = 1/800 => r^2 = 1/800 x pi => r = 0.0199 =0.02 ( app.) so diameter should be d= 2xr = 0.04 cm 2.resistance of the wire, R = V / I = 2 / 4 = 0.5 ohm , length L = 1m, area A = 1.0mm^2 = 1 x 10 ^-4m^2 conductivity of the wire will be = L /RA = 2 x 10^4 3.power,P = 0.54w E = 3v R = E^2/P = 50/3 ohm when connected with 1.5v, power dissipated = 1.5^2 /R = 0.135 w