E&M > Electromagnetic Induction > Induced Currents and Forces

DCS# 5K10.60

---

EARTH INDUCTOR

---

---

APPARATUS

earth inductor	202-20-D
shielded cable	202-20-D
storage scope with camera	202-08-B-1

---

DESCRIPTION

The flip coil will rotate through 180º when released.  The changing flux in the coil due to the earth's magnetic field induces a voltage which is displayed on the scope.  The magnitude of the earth's field can be determined from the area under the curve.

 

NOTES

The coil can be oriented to measure the vertical or horizontal component or the total field.

Integrated area = ∫ε *dt = 2NΦ = 2NBA

N = 1000 turns

r = 11.0 cm

The frame of the flip coil should be connected to the oscilloscope ground.

Scope settings: 5mV/div, 50 ms/div.

The earth's magnetic field is 54 uT at 69º inclination in Oberlin, according to the NGDC magnetic field calculator.

The storage scope can be replaced with a computer running LoggerPro and the instrumentation amplifier.  LoggerPro has a built-in function for finding the area under the curve.   The plot shown here was obtained for the vertical component of the earth's magnetic field: