# Homework Help: Width of Slicon Strip?

1. Sep 23, 2007

### mrlucky0

1. The problem statement, all variables and given/known data

A strip of doped silicon 270 µm wide contains 9.1E22 conduction electrons per cubic meter and an insignificant number of holes. When the strip carries a current of 110 µA, the drift speed of the electrons is 44 cm/s. What is the thickness of the strip?

2. Relevant equations

I=n*e*A*V

Where I is current, n is electrons per volume, A is cross sectional, v is drift velocity

3. The attempt at a solution

I've plugged into the equation above the variables given in the problem and solved for area. But how to find thickness, given the width? I think there's a missing link somewhere.

2. Sep 23, 2007

### aaroman

Think about it: which area is that?

3. Sep 23, 2007

### mrlucky0

It's the surface area of the strip. I've thought about it. I have the width and the surface area but I cannot solve for thickness.

4. Sep 23, 2007

### mgb_phys

No it's the cross sectional area of the strip - does this help you find the thickness?

5. Sep 23, 2007

### mrlucky0

Yes, just divide that by the width. Thanks!