Magnetic Field Lab

7/31/2019 Magnetic Field Lab

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Group Members Eamon BarkhordarianKabir Gill 3/25/12Malik Gill Period CShang Yip Kompella

Magnetic Field Lab

Purpose : to explore factors that affect the magnetic field inside the solenoid and study how

the field varies in different parts of the solenoid. Also to determine the vacuum permeabilityconstant 0 through the relationship between magnetic field and the number of turns per meter inthe solenoid.

The objective of this lab is to understand and discover the properties of the magnetic field of asolenoid and the field variations over certain areas. Also direction and shape of the magneticfield lines will be determined. The effects of several variables on the magnetic field strength suchas the vacuum permeability constant 0 through the relationship between magnetic field and thenumber of turns per meter in the solenoid will be explored.

Background : Electrical currents create magnetic fields and the simplest way to create a uniformmagnetic field is to run a current through a solenoid of wire.

For a long solenoid of many turns, the B-field within is nearly uniform, while the field outside isclose to zero. The field within the coil can be calculated from Amperes Law.

Magnetic Field: A region around a magnetic material or a moving electric charge within whichthe force of magnetism acts.

Solenoid: A cylindrical coil of wire acting as a magnet when carrying electric current.

Current: amount of electrical charge transferred per unit timeForce (F)= charge (q) * velocity (v) * field strength (B)

B= F/ qv

Procedure :

1. We connected to Vernier Magnetic Field Sensor and set the amplification to x200.2. We stretched 100 rings of the wire 1 meter in length, and had tape hold the wire in its position.

3. We used banana alligator clips to connect the Slinky to the power supply.

4. We turned on the power supply to 2.0 A on the ammeter with the closed switch.

5.We opened the logger pro file for this lab.


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Part I:

6. We held the switch closed and placed the Magnetic Field Sensor between the turns of theSlinky near its center.

7. We stuck the magnetic field Sensor through different locations along Slinky to explore howthe field varies along the length.

Part II:

10. We adjust the power supply so that the current will be 2.0 A when the switch is closed.

11. We held the magnetic sensor in one position and clicked to zero the sensor.

12.We clicked the collect data button to begin data collection. The power supply was on for 10seconds.

13. We found the average field while the current was on by clicking on the Statistics button. Werecorded the length of the Slinky and the average field in the data table.

14. We repeated previous steps after changing the length of the Slinky from 0.5 m, 1.5 m, to 2.0m.

Schematic Drawing:


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Data Table

Length of Solenoid (meters) Turns per meter n (m -1) Magnetic field B (mT)

1.0 100 0.34250.5 200 0.3597

2.0 50 0.2945

1.5 66.67 0.3140

0.75 133.33 0.3456


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Caption: Looking at the graph we can see that the turn density and the magnetic field strength aredirectly and positively related. This further supports Amperes Law. Amperes law states thatthere is an attractive or repulsive force between two parallel wires carrying an electric current.

r2 Value: The r 2 value of .829 proves that the linear fit model accurate describes the relationshipbetween turn density and magnetic field strength.


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Analysis :

The general pattern that we noticed in our data was the direct proportionality and linearity

between magnetic field strength and turns per meter. There was a strong positive relationshipbetween the two axis. Our r squared value of .829 showed that the linear approximation was theappropriate model and trend fit estimator for our data. The slope of the line was calculator to be.0004 mT m. That means when the turns per meter increases by one, the magnetic field strengthincreases by is .0004 mT.

Our data gave us a u value of 2.0 x10 -7 which we found had a percentage error of 68%blow when compared to the actual value of what is.

Our general idea and goal was generally attained. We were able to discover that thenumber of turns per meter directly causes and relates to the change inside the magnetic field. Wealso found the linear relationship between the magnetic field and the turn density. We also foundthe vacuum permeability constant. We received the number 2.0 x 10 -7 C2 /Nm 2 resulting in a68% error.

One potential error that could have impacted our results was that we might not have beenexactly consistent with our current amount. We had to manually adjust for 2 amperes every timeand could have been in such a rush for time that we did not provide exactly 2 amperes. Withoutsome kind of regulation for the current every time, this would be very hard to limit and eliminateerror. Higher current would increase the magnetic field and lower current would decrease themagnetic field, consequently increasing or decreasing our u value.

Another error could have been that we were not perfect motionless where we werezeroing the data at the beginning. Making that simple mistake in the beginning by possiblytwisting the sensor even slightly could have very big effects on our resulting data. Thismovement would give different readings for the magnetic field.

Magnetic Field Lab

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