1 Attachment(s)

Physics help needed about magnetic induction

Since I posted this topic I need URGENT help and additional explanations approximately within 12 hours.

Please look at the attachment and read my problem.

What is the induction at infinity ?

I told teacher it to be 0 but she disagreed.

Using the formula for calculating induction and substituting big distances into the formula gives me also 0.

I had a solenoid and its lenght was 0,222 meters. The diameter of the solenoid was 120 mm.

My goal was to measure the magnetic induction of the solenoid at solenoid axis. The current that runs through solenoid is a sinusoidal AC.

The coil was used to measure magnetic induction. At the axis

the voltmeter shows me that at the center of solenoid the voltage is about 0,40 Voltage. Moving away from the point at center reduces the voltages. In other words about 12 cm away from the center shows me that the voltage is 0,18 V. Why does moving away from the center point at solenoid reduces voltages ?

The formula for calculating magnetic induction at certain distances from the center point was:

induction = (l/2 - x)/sqare root((l-2x)^2+D^2) + (l/2 + x)/sqare root((l+2x)^2+D^2) where l is length of solenoid and D is diameter of solenoid.

The condition l >> D is not satisfied.

I was told that magentic field was homogenous. Why does the voltages reduces if magnetic field is homogenous ?