- #1

- 6

- 0

## Homework Statement

I'm doing a physics demo, and I've made basic electromagnet using some copper wire, a 6 volt battery, and a carbon steel screw, and I need help checking my calculations because I think the magnetic field for my magnet is too large. I've double checked everything and can't come up with why it's so large....(The reason I think it's not nearly as strong is I have a a neodymium magnet to compare it with, which has ~ 1.25 T B field, and although it is close to it's strength, it is not as strong). The only thing that makes the B-field believable to me in terms of strength is removing the relative permeability constant.

Variables used in my calculations:

Wire characteristics: 7.3152 m, 16 AWG (cross sectional area of 1.330763e-6 m2)

Solenoid Core: .135m long carbon steel screw with a radius of approx 0.05m

6 volt battery

μ0 = 4π × 10−7 H/m

μ

_{carbon steel}1.26×10−4 H/m

## Homework Equations

R=ρl/A

I = V/R

B=kμ0nI

## The Attempt at a Solution

[/B]

Wire: 24 ft. (7.3152 m), 16 AWG

Solenoid Core: 0.135m long Carbon Steel Screw with a radius of approx. 0.05m

Carbon Steel magnetic permeability (μ) = 1.26e-4 H/m => a relative permeability of ~100 (μ/μ0)

Resistance = ρl/A

ρ = 1.724e-8 ohm*m, l = 7.3152 m, A= 1.330763e-6 m2

Resistance = 0.0964 ohms

I = V/R

V = 6 V, R = 0.0964 ohms => I= 62.2118 Amperes

B=kμ0nI μ0 = 4πe-7 T*m/A n= 143 turns/0.135 m = 1059.259259 turns/m k=relative permeability of carbon steel = 100

B = (100)(4πe-7 T*m/A)( 1059.259259 turns/m)( 62.2118 Amperes) =

**8.281 Tesla**
Last edited: