Starter What effect does an iron core have on the magnetic field of a coil? ( What role does the nail play?) What effect does an iron core have on the.

Starter

What effect does an iron core have on the magnetic field of a coil? ( What role does the nail play?)

Magnetic Field of a Coil The magnetic field inside a coil that has N turns, is L long, and has a current of I, is given by:

B = moiN/L

i = current in amps N = # of turns L = length in meters mo = 1.25 x 10-6

ExampleFind the magnetic field inside a coil that is 8cm long, has 3000 turns, and carries a current of 1.00 amp.

B = moiN/L = (1.25 x 10-6 )(1.00)(3000)/.08 = .0469T

Note: Gauss is another common unit for B-fields

( 10,000 Gauss = 1Tesla)

so B = .0469T( 10,000Gauss/1 Tesla) = 469 Gauss

Iron Core SolenoidsThe magnetic field inside a coil that has N turns, is L long, has a current of I, and has an iron core is given by:

B = kmoiN/L

i = current in amps N = # of turns L = length in meters mo = 1.25 x 10-6 k ≈ 200 for iron

ExampleFind the magnetic field inside a coil that is 8cm long, has 3000 turns, and carries a current of 1.00 amp, and has an iron core.

B = kmoiN/L = 200(1.25 x 10-6 )(1.00)(3000)/.08 = 9.38T

Starter

Which direction is the magnetic field in the center of the coil?Right or Left?

Starter

Which battery terminal is positive, and which is negative?

Magnetic Field of a Coil The magnetic field inside a coil that has N turns, is L long, and has a current of I, is given by:

B = moiN/L

i = current in amps N = # of turns L = length in meters mo = 1.25 x 10-6

Part 1: Magnetic Field of a Coil

Data Part 1

Logger-proUsing the Vernier magnetic field detector, a coil, the power supply onthe circuit board, and a current sensor, determine the magnetic field inside two different coils for a given current. Use this value todetermine the number of turns in each coil.

N = (BL/moi)

Coil Description Length, L(m) Current I(A) Magnetic Field, B(T) N ( calculated)

Part 2 The Earth’s Magnetic Field

Vernier – Loggerpro Using the Vernier magnetic field detector:

1. Determine the magnetic field of the Earth by rotating the magnetic field sensor until you obtain the largest reading possible. 2. Determine the Inclination of the field in degrees. This is the angle between the horizontal and the sensor. 3. Check your data with NOAA website. http://www.ngdc.noaa.gov/geomag-web/

Part 3 The Field of a Bar Magnet

Vernier – Loggerpro 1. Using the Vernier magnetic field detector: Determine how the magnetic field of a bar magnet depends on the distance from the end of the magnet. 2. Plot B vs. x. and fit with a smooth curve. Distance From Magnet

(cm)Magnetic Field

(T)2468

101214161820

Connection

Where do you encounter magnetic coils every day?

Questions

1. How did you values of the Earth’s Magnetic Field and Inclination compare to the NOAA values?

2. Is the relation between the B -field of a bar magnet and the distance from the end linear? Explain.

Exit

Write down the formula for the B-field in a coil and describe each term.

Report Checklist

A. Part I Data table with Calculations Shown

B. Part II Experimental value of B for Earth and Inclination Angle

C. Part II NOAA Value for B and Inclination Angle

D. Part III Data table and Graph

E. Questions

F. Starter

G. Connection

H. Summary