# Electric field in a platinum wire

#### sdevoe

1. Homework Statement

Consider a platinum wire (σ = 1.0e+7) with a cross-sectional area of 1 mm^2 (similar to your connecting wires) and carrying 0.3 amperes of current, which is about what you get in a circuit with a round bulb and two batteries in series. Calculate the strength of the very small electric field required to drive this current through the wire.

2. Homework Equations

σ=qnu
I=qnAuE
Therefore I=σAE
where phi is the conductivity A the cross sectional area and E the electric field

3. The Attempt at a Solution
This seemed easy but i got an answer of 3e-5 and that is incorrect?

Related Introductory Physics Homework Help News on Phys.org

#### sdevoe

Never mind i figured it out

#### tkrzeminski3

How did you do it? I am where you were in the first post.

#### tkrzeminski3

Hey I figured it out.
The only problem was dealing with units.
I just multiplied the 3e-5 by 1000 and got .03 as the right answer.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving