What is the resistance of a copper wire of 2 km long and 0.50 mm diametre if the resistivity of copper is 1.7 ×10^-6 ohm meter?
R = ρ*l/Awhere R is resistance in ohm, ρ is resistivity in Ω-metre, l is length in metre & A is cross sectional area in m^2.Given,ρ = 1.7 * 10^-6 Ω-metrel = 2,000 metre (2 km)A = π*r^2 = π*(0.0005/2)^2 m^2 = 1.9635 * 10^-7 m^2(Since 0.5 mm= 0.0005 m & Radius is half of diameter)So,R= (1.7 * 10^-6 )* 2000 / (1.9635 * 10^-7) Ωor, R= 17,316.05 Ω or 17.316 kΩ
How to test the resistance of the wire?
This is for a school project and needs to be at GCSE standards, no more advanced than that please! I conducted an experiment on the resistance of a wire, measuring the voltage and the current on a circuit with a metre long wire and shortening the wire and repeating the experiment until I had all the data I needed. I then used Ohm's law to calculate the resistance of the wire at different lengths and I am currently writing up a conclusion. However to achieve a higher grade I need to mention a different experiment I could perform to get more reliable data, and that's what I'm asking, what similar yet more reliable practical could I perform in order to get similar results to back up my conclusion (of course, this is hypothetical so I don't need too much detail). Thanks in advance -Cryson
What is temperature coefficient of resistance?
In electrical engineering or in electronics, we know that when current flows through any wire, it gets heated up due to the resistance of the wire. Heating is the product of i squre * resistance ( squre of current into value of resistance).In ideal condition, resistance should be zero but that does not happen, that is only imaginary. Now when heating is there, resistance of a wire or a conductor changes with temperature. Although, it is desired that resistance should remain constant and it should be independent of the temperature. Thus, the change of resistance per degree change in temperature is called Temperature Coefficient of resistance, normally it is represented by a symbol Alpha:For pure metals, it is positive, means the resistance increases with temperature. For the elements like carbon, silicon, and germanium, this coefficient is negative, means the resistance decreases with increasing temperature. Thus, to make highly precise resistances where resistance does not change alloys are required.
A copper-constantan thermocouple generates a voltage..? Physics problem?
A copper-constantan thermocouple generates a voltage of 4.99 x10^-3 volts when the temperature of the hot junction is 108.9° C and the reference junction is kept at a temperature of 0.0° C. If the voltage is proportional to the difference in temperature between the junctions, what is the temperature of the hot junction when the voltage is 2.08 x10^-3 volts?