Electromagnetic fields 2 Lab Report PDF

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My detailed lab reports from Physics 2 Lab with Dr. Sorci....

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Ex pe r i me nt8:El e c t r oma gne t i cFi e l ds Apr i l7, 201 6

I. PURPOSE The purpose of this experiment was to determine the wavelength of a visible and microwave waves using interference patterns according to the nature of light and EM radiation. II. THEORY At one point, electricity and magnetism were thought to be completely separate. A mathematician named Maxwell made the deduction that a wave of self propagating electric fields could simultaneously produce magnetic field waves that are in phase and traveling in the plane perpendicular to the electric field. These ways composing of both electric fields and magnetic fields are known as electromagnetic waves. Visible light, microwaves, X-rays, gamma rays, infrared light, and ultraviolent light are all examples of electromagnetic waves. These electromagnetic waves have different wavelengths but they travel at the same speed of 3x108 m/s in a vacuum. This speed is commonly referred to simply as the speed of light. Visible light is the only electromagnetic wave that can be physically seen by human eyes. Humans have evolved the ability to see the spectrum of sunlight after it passes through the atmosphere. Visible light has wavelengths between 400 to 700nm. Each color has a different wavelength. Humans cannot see wavelengths above or below this range. In contrast, microwaves have wavelengths in the length of centimeters, and cannot be seen by the naked eye. Since wavelength and frequency are inversely proportional, as the wavelength increases, the frequency of a wave decreases. Light travels as a wave, as demonstrated by Young’s Double Slit experiment. Light patterns can be visualized when slight is passed through a double slit. The bright and dark spots can be marked, and by measuring the distance between the distance between each

maxima and minima can be determined for the light waves. The same can be done with microwaves, but since microwaves cannot be seen a device must be used to detect the pattern made by the microwaves.

|GAV −mean|

% error=

GAV

× 100

Standard deviation:

sin θ=

y L

max λ=

min λ=

d sin θ m

d sin θ 1 m+ 2

III. PROCEDURE 8.1 Visible Light 1. Set laser at one end of optical bench. Place double slit holder directly in front of laser. 2. Place screen at other end. 3. Turn on laser and observe pattern.



If patter is not clear switch double slits or adjust knobs on laser. Be sure light is shining through double slits.

4. Record size of double slit. 5. Measure distance between slits and screen (L). 6. Place piece of copy paper on screen and tape it flat to screen. 7. Use pencil to mark a dark line at the center of the middle bright spot. 8. Draw lines through consecutive centers of the bright spots for 5 spots on either side. 9. Remove paper and measure the distances between bright spots on either side of line (m=1).

8.2 Double Slit for microwaves 1. Place receiver on moveable end while source is placed on fixed side of apparatus. 2. Measure distance between double slits. 3. Double slit should be placed in the center using the magnetic holders. Line the zero of dial with receiver. 4. Turn on Microwave source and move receiver till you have a nice max value on dial. 5. Move receiver until you find first minimum. Record angle for this position. Always record angle from zero. 6. Move receiver to find the next max and record the angle. 7. Repeat this for 2 of each. 8. Return receiver to the center and repeat going in opposite direction. During the course of this experiment, I make the lines on the paper and assisted my lab mates in setting up the experiment. In addition, I recorded measurements and worked out my own calculations.

V. ANALYSIS

VI. CONCLUSION During this experiment, the wavelength of a visible light wave and a microwave was determined. For the first part of this experiment, the size of the double slit (d) was 0.0255cm and the length between the the slits and the screen (L) was measured to be 113cm. The sin of the light wave was calculated to be 0.0023 when the distance between spots was 0.5cm, 0.0044 when the distance between spots was 1.00cm between spots, 0.0060 when the distance between spots was 1.6cm between spots, and 0.0079 when the distance between spots was 2.1cm. To find y, the measured distance between spots was divided by two. The wavelength of the light wave was calculated to be 5.865 x 10-5cm when the distance between spots was 0.5cm, 5.615 x 10-5cm when the distance between spots was 1.00cm, 5.1 x 10-5cm when the distance between spots was 1.6cm, and 5.04 x 10-5cm when the distance between spots was 2.1cm. The average wavelength was calculated to be 5.40 x 10-5cm with a calculated standard deviation of 3.99 x 10-6cm, resulting in a percent error of 20%. For the second experiment, the distance between the double slits was measured to be 5.7cm. The first clockwise minimum had a measured angle of 14 and a calculated wavelength of 2.758cm for the microwave. The first clockwise maximum had a measured angle of 26  and a calculated wavelength of 2.499cm. The second clockwise minimum had a measured angle of 36 and a calculated wavelength of 2.234cm. The first clockwise maximum had a measured angle of 51 and a calculated wavelength of 2.215cm. The first counterclockwise minimum had a measured angle of 14 and a calculated wavelength of 2.758cm. The first counterclockwise maximum had a measured angle of 25 and a calculated wavelength of 2.409cm. The second counterclockwise minimum had a measured angle of 36 and a calculated wavelength of 2.234cm. The second counterclockwise maximum had a measured

angle of 47 and a calculated wavelength of 2.084cm. The average wavelength was calculated to be 2.399cm with a standard deviation of 0.255. Overall, this experiment can be considered a success despite some human error. The wavelengths for both the microwave and the light wave were determined, and the values were close to expected values. Light has a smaller wavelength than the microwave, and the calculated microwave wavelength was in the centimeter range, as expected. For the light wave, the percent error can be attributed to human error while marking the sheet of paper. Lines were not accurately directly between each bright spot, leading to error in measured distances, due to how the paper was set up. The microwave experiment had a very small standard deviation. This was small deviation was likely due to environmental interference....