Question

Design an experiment to determine the strength of the magnetic field of Earth using the available equipment.

Available equipment: A large coil of wire (with stand in the center), compass, ammeter, 10Ω and 50Ω resistors, power supply, ruler.

A) Perform the experiment and record your measurement and calculations in an appropriate format. Be explicit about what model you're using to calculate the magnetic field. Vector diagrams may assists you. Include important measurements. Determine the magnitude of the Earth's magnetic field.

B) Identify at least 3 sources of error in your experiment and evaluate how they affect your data. Identify at least 1 shortcoming in your experimental design and what you would do to fit it, Summarize these. Hints: Just saying human error is not acceptable.

Please show the calculations and how you got the answers.

Answer 1

Objective: The objective of this experiment is to measure the magnitude of Earth’s magnetic field.

Let us perform Experiment:

A typical compass is constrained to 2 dimensions and rotates to point to Earth’s magnetic south pole, which is (approximately) geographic north. Earth’s magnetic field, however, is a 3 dimensional phenomenon. It has components that point into and out of the earth, not just along the surface. We need to measure at our location the direction of the total magnetic field of Earth (the angle theta). To determine field declination, theta, we will use a dip needle. A dip needle (see below figure) is a compass that rotates. It measures both horizontal and vertical angles. First, arrange the dip needle in a horizontal position, compass needle and bracket aligned, pointing north (normal compass). Refer to Fig.below, for clarification. The needle should align with 270 degree.

Now rotate the compass 90 degree (Fig.below) to a vertical position. The needle rotates to a new angle; the difference between the initial angle and the final angle is the angle theta. From Fig.below, we see that the dip needle points in the direction of Earth’s total magnetic field at our location.

By determining the magnitude of the horizontal component of Earth’s magnetic field, Be, using alpha, and measuring the direction of Earth’s total magnetic field, Bt, using theta, the magnitude of Bt can be determined.