Calculating Resistance of Composite Wire: Copper and Iron Combination

[BuBbLeS01]

Resistance of Wire...HeLp!

Homework Statement

A 122-cm-long wire is made by welding a 0.36-mm-diameter, 21-cm-long copper wire to a 0.47-mm-diameter, 101-cm-long iron wire. What is the resistance of the composite wire?

Homework Equations

The Attempt at a Solution

How do I do this since it is made up of 2 different materials?

 

[BuBbLeS01]

do I just find the resistance of each one and add them?

 

[Shooting Star]

Resistances in series add up.

 

[BuBbLeS01]

how do I know they are in series?

 

[mikecal1]

Yea They are not clear on that point do they mean the wires were welded end to end to make a longer wire, OR as is the case sometimes, were the two wires used in parralel to make a thicker wire. I assume ened to end ie series as the person writing the problem would most likley have said welded at both ends if he/she meant paralell. So calculate resistance of each piece and simply add

 

[BuBbLeS01]

Yea They are not clear on that point do they mean the wires were welded end to end to make a longer wire, OR as is the case sometimes, were the two wires used in parralel to make a thicker wire. I assume ened to end ie series as the person writing the problem would most likley have said welded at both ends if he/she meant paralell. So calculate resistance of each piece and simply add

oh ok...thank you!

 

[Ignea_unda]

Homework Statement

A 122-cm-long wire is made by welding a 0.36-mm-diameter, 21-cm-long copper wire to a 0.47-mm-diameter, 101-cm-long iron wire. What is the resistance of the composite wire?

If you re-read you have a 21-cm wire and a 101-cm wire. Therefore the only way this problem can work would be to have them end to end to have a 122-cm wire.

So, yes, as has been said above, just calculate both the resistances and add them together.

 

[mikecal1]

Great catch Ignea, my bad I read problem way too quick! gets me killed every time