1. what diameter must a copper wire have its resistance is the same as that of an equal length of aluminum wire with diameter 3.26mm?
p copper = 1.72x10-8 ohm-meter
p al. = 2.83x10-8 ohm-meter
2. a battery powered light bulb has a tungsten filament when the switch connecting to the bulb to the battery is the first turned on & the temp. of the bulb is 20 Celsius, the current in the bulb is 0.86Amp.. After the bulb has been off for 30secs. the current is 0.22Amp.. what is the final temperature of the filament?
alpha of 20degree = 0.0045/degree Celsius(tungsten)
3. you apply a potential difference of 4.5V between the ends of a wire that is 2.50m in length and 0.654mm in radius the resulting current through the wire is 17.6A what is the resistivity of the wire?
pls show me the solution and explain it to me..i need your help pls answer it..tnx..