Electric current flowing in a nichrome wire

In summary, Dx has a problem involving a nichrome wire with a radius of 0.5 mm and a resistivity of 100 x 10^-8 ohm.m. They are trying to use Ohm's law to find the voltage across the wire, but are struggling to set up the equation correctly. Tom points out that they have mistakenly used the resistivity instead of the resistance, and suggests calculating the resistance using the given information. After taking a break and re-reading the section on resistivity, Dx is able to correctly set up the equation and solve for the voltage. They thank Tom for their help.
  • #1
Dx
Hiya!
I have a problem that's got me confused to solve. I want to use ohms law but not right. Here is the problem.

A nichrome wire has a radius 0f .5 mm and resistivity of 100 x 10^-8 ohm.m. If the wire carries a current of .5 A what is the voltage across the wire? The length of the wire is .32m

E = .5A x 100 x 10^-8 ohm is what i have for setting it up but its not the answer. what do i need to do to solve for this?

Dx :wink:
 
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  • #2
Originally posted by Dx
A nichrome wire has a radius 0f .5 mm and resistivity of 100 x 10^-8 ohm.m.

Note: You were given the radius and the resistivity. You were not given the resistance.

E = .5A x 100 x 10^-8 ohm is what i have for setting it up but its not the answer.

The problem is that you plugged the resistivity in for the resistance.

what do i need to do to solve for this?

Calculate the resistance, then use E=IR.
 
  • #3


The problem is that you plugged the resistivity in for the resistance.

Calculate the resistance, then use E=IR. [/B][/QUOTE]

Ok i have the .5A but no E or R to perform ohms law with how do i solve for this please Tom.

Dx, :wink:
 
  • #4


Originally posted by Dx
Ok i have the .5A but no E or R to perform ohms law with how do i solve for this please Tom.

1. They ask you for E.
2. They give you enough information to find R.

Look up the deinfition of resistivity, and you will see how it is related to the dimensions of the wire. Come on, this is easy. You can do it.
 
  • #5
So Happy!

Thank You, Tom!

You know i looked at that section numerous times but after taking a days break and reading what you wrote it was like a lightbulb lit up in my head. I can't believe I didnt see it earlier always the simple ones that seem to give me the most trouble.

I found the formula R = p(L/A) then converted it to amps using ohms law.

Much appreciated, you helped me alot!
Dx :wink:
 

1. How does electric current flow in a nichrome wire?

Electric current flows in a nichrome wire due to the movement of electrons. When a voltage is applied to the wire, the valence electrons in the wire start to move, creating a flow of electric current.

2. Why is nichrome wire commonly used for heating elements?

Nichrome wire is commonly used for heating elements because it has a high melting point, is corrosion resistant, and has a high electrical resistance. This makes it ideal for converting electrical energy into heat.

3. Does the thickness of a nichrome wire affect the flow of electric current?

Yes, the thickness of a nichrome wire does affect the flow of electric current. Thicker wires have lower resistance and can handle a higher current, while thinner wires have higher resistance and can only handle a lower current.

4. What factors affect the resistance of a nichrome wire?

The resistance of a nichrome wire is affected by its length, thickness, and temperature. Longer wires have higher resistance, while thicker wires and higher temperatures have lower resistance.

5. How does the temperature of a nichrome wire affect its resistance?

The temperature of a nichrome wire affects its resistance because as the temperature increases, the atoms in the wire vibrate more, causing more collisions with the flowing electrons. This increases the wire's resistance and decreases the flow of electric current.

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