I have a question on conducting electricity there was a question in this physics book and I was confused!?

Question

so I was looking through this physics book to brush up my knowledge and I came across this:

A student compares four different wires to see which is best conductor of electricity. He passes a current of 0.8A through each wire and measures the voltage needed.

His results are as follows
alluminium 2.4
copper 1.6
slver 1.4
steel 24.0

Which is the best conductor and why? Explain

Also how to calculate the resistance of the silver wire?
Show the working and state the formula that you use please.

while doing this he notices one of the wires gets warm.
whych is most likely to get noticably warm?
calculate the power of this wire
show the working and state any formula


why are many over heated power cables made out of alluminum with a steel core?

Answer 1

Ohm's Law:

V=IR

V=voltage, I=current and R=resistance.

So, resistance=voltage/current

The best conductor is the wire with the lowest resistance, silver (Ag).

Al is used in because it is a good conductor and it is inexpensive compared to silver.

The heating up comes for the fact that if the resistance is higher, then energy is being transferred to the cable, which appears as an increase in thermal energy. Steel has a high resistance, hence heats up more than Al, Ag etc. So cables made with steel tend to heat up.

Power=IV=RV^2

Answer 2

Voltage = Current times Resistance (V=IR)

Since you are comparing the voltage required to push the same amount of current, the lower the voltage the better as the voltage is basically a measure of how easily current can be pushed.

From the above equation, take your voltage and divide by your current, and you get the resistance. Again, the smaller the resistance, the better the conductor of electricity.

Power = Voltage times Current.

So the one that uses the most power is the one that's running with the highest voltage, and the higher voltage is essentially a greater force involved in pushing electrons through that wire, and this higher force is translated into hotter burning wires. Hope this explains why steel core wires overheat more easily.

Answer 3

The one with the lowest voltage is the best conductor. Ohm's law states E=I*R, but R=1/G, where R = resistance and G = conductance. Thus E = I/G; the higher G produces lower E. Using Ohms law on the silver wire R = E/I, so the resistance is 1.4/.8 ohms

Answer 4

resistance= voltage\ current
hence, resistance of aluminium= 2.4\0.8=3 ohms
similarly for copper it is, 1.6\0.8= 2 ohms
silver, 1.4\0.8= 1.75 ohms
steel 24\0.8= 30 ohms
the best conductor is therefore silver because it offers the lest resistance to the flow of electric current.

the resistance of the silver wire has already been calculated above.

Answer 5

Silver is the best conductor. Because I=U/R , and the resistance is lowest.

Answer 6

sure Brass is an alloy of two metallic (copper and zinc) and both habit electrical energy ( as do ALL metals). They habit by technique of electrons entering at one end and those then migrate down as a chain and fall off at the different end. Electrons are small sub-atomic debris that orbit the nucleus of all atoms.

Answer 7

Silver, as it has the least resistance.

V= IR

1.4 = .8R

Roughly 1.75

For the resistance