To study the earth's magnetic field using a tangent galvanometer

Physics Lab Report 2

Lab Manuals (contained within each week)
KET simulations: http://virtuallabs.ket.org/physics/. Students will receive an e-mail from the KET Virtual Physics Labs with an invitation to enroll into the class.

PhET Interactive simulations: http://phet.colorado.edu/en/simulations/category/physics.

Expression of the experimental results is an integral part of science. The lab report should have the following format:

Cover page (10 points) - course name (PHY 132), title of the experiment, your name (prominent), section number, TA’s name, date of experiment, an abstract. An abstract (two paragraphs long) is the place where you briefly summarize the experiment and cite your main experimental results along with any associated errors and units. Write the abstract after all the other sections are completed.
The main body of the report will contain the following sections, each of which must be clearly labeled:

Objectives (5 points) - in one or two sentences describe the purpose of the lab. What physical quantities are you measuring? What physical principles/laws are you investigating?
Procedure (5 points) - this section should contain a brief description of the main steps and the significant details of the experiment.
Experimental data (15 points) - your data should be tabulated neatly in this section. Your tables should have clear headings and contain units. All the clearly labeled plots (Figure 1, etc.) produced during lab must be attached to the report. The scales on the figures should be chosen appropriately so that the data to be presented will cover most part of the graph paper.

Results (20 points) – you are required to show sample calculation of the quantities you are looking for including formulas and all derived equations used in your calculations. Provide all intermediate quantities. Show the calculation of the uncertainties using the rules of the error propagation. You may choose to type these calculations, but neatly hand write will be acceptable. Please label this page Sample Calculations and box your results. Your data sheets that contain measurements generated during the lab are not the results of the lab.
Discussion and analysis (25 points) - here you analyze the data, briefly summarize the basic idea of the experiment, and describe the measurements you made. State the key results with uncertainties and units. Interpret your graphs and discuss what trends were observed, what was the relationship of the variables in your experiment. An important part of any experimental result is a quantification of error in the result. Describe what you learned from your results. The answers to any questions posed to you in the lab packet should be answered here.
Conclusion (5 points) - Did you meet the stated objective of the lab? You will need to supply reasoning in your answers to these questions.
Overall, the lab report should to be about 5 pages long.

Each student should write his/her own laboratory report.

Duplicating reports will result in an "E" in your final grade.

All data sheets and computer printouts generated during the lab have to be labeled Fig.1, Fig. 2, and included at the end of the lab report.

Lab report without attached data sheets and/or graphs generated in the lab will automatically get a zero score.

Magnetism

Magnetic fields affect moving charges.

Moving charges produce magnetic fields.

Changing magnetic fields can create electric fields.

Introduction

www.

www.ahmedmater.com

1

Magnets

Two poles, called north and south

Like poles, repel each other and unlike poles, attract each other.

Magnetic poles cannot be isolated.

Section 19.1

http://www.ece.neu.edu/faculty/nian/mom/work.html

Magnetic Fields Sources

The region of space surrounding a moving charge includes a magnetic field.

The charge will also be surrounded by an electric field.

A magnetic field surrounds a properly magnetized magnetic material.

Section 19.1

Magnetic Fields

A vector quantity symbolized by

North pole of a compass needle points in the direction of magnetic field vector at that location.

Section 19.1

Magnetic Field Lines, Sketch

A compass can be used to show the direction of the magnetic field lines (a).

A sketch of the magnetic field lines (b)

www.ahmedmater.com

Earth’s Magnetic Field

Section 19.2

Magnetic Fields

The magnitude of the magnetic force is

F = q v B sin θ

This force is zero when the charge moves along the field lines (θ= 0) and is maximum when the charge moves perpendicularly to the magnetic field lines (θ = 90).

Section 19.3

Units of Magnetic Field

The SI unit of magnetic field is the Tesla (T)

- Wb is a Weber

The cgs unit is a Gauss (G)

- 1 T = 104 G

Section 19.3

Finding the Direction of Magnetic Force

The direction of the magnetic force is always perpendicular to both and

Fmax occurs when ┴

F = 0 when II

Section 19.3

Right Hand Rule #1

Point your fingers in the direction of the velocity.

Curl the fingers in the direction of the magnetic field,

Your thumb points in the direction of the force on a positive charge.

If the charge is negative, the force is directed opposite that obtained from the right-hand rule.

Section 19.3

Force on a Wire

The magnetic field is directed into the page.

- The x represents the tail of the arrow.

Green dots would be used to represent the field directed out of the page.

- The • represents the head of the arrow.

I =0 therefore F = 0.

Section 19.4

Force on a Wire

B is into the page.

The force is to the left (b).

The force is to the right (c).

Section 19.4

Force on a Wire, Equation

F = B I ℓ sin θ

θ is the angle between and the direction of I

The direction is found by the right hand rule, placing your fingers in the direction of I instead of

Section 19.4

Particle Moving in an External Magnetic Field

Section 19.6

Magnetic Fields – Long Straight Wire

The compass needle deflects in directions tangent to the circle and points in direction of the magnetic field.

Section 19.7

Direction of the Field of a Long Straight Wire

Right Hand Rule #2

Grasp the wire in your right hand.

Point your thumb in the direction of the current.

Your fingers will curl in the direction of the field.

Section 19.7

Magnitude of the Field of a Long Straight Wire

µo = 4 π x 10-7 T.m / A

µo is called the permeability of free space

Section 19.7

Magnetic Force Between Two Parallel Conductors

The force per unit length is:

Section 19.8

Magnetic Field of a Current Loop

All the segments, Δx, contribute to the field, increasing its strength.

Section 19.9

Magnetic Field of a Current Loop

The magnetic field lines for a current loop resemble those of a bar magnet.

Magnetic Field of a Current Loop – Equation

The magnitude of the magnetic field at the center of a circular loop

With N loops in the coil, this becomes

Section 19.9

Magnetic Field of a Solenoid

B = µo n I

n is the number of turns per unit length

n = N / ℓ

Section 19.9