Mrs. Meer Name_____________________________ #_____
Chemistry Date______________________ Period_________

Thomson’s Experiment Revisited

While Fred was babysitting his younger brother, Phil, he noticed that Phil was trying to stick a magnet on the screen of their black-and-white television. The magnet did not stick to the glass, but the picture seemed to be distorted. The closer he held the magnet to the screen, the more the images bent. Fred asked Phil if he could try an experiment with the magnet. When Fred touched the magnet to the screen, the image curved away from the magnet in one direction. When he turned the magnet around and tried again, the image curved away in the other direction. When he waved the magnet back and forth across a part of the screen, the distortion in the images followed the magnet. (CAUTION: Do not try this activity on your own television screen at home.)

1. The image on the television screen is produced when electrons hit the phosphorus coating and cause it to glow. Why did Fred’s magnet affect the image on the screen?
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2. Why did the image curve away from the magnet in a different direction when the magnet was reversed?
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3. If Fred had two bar magnets, could he have placed them near the screen without causing any distortion in the image? Explain.
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4. Describe the effects a stronger magnet would have had on the television image.
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5. Speculate about how the television controls the electron beam that is continually scanned across and down the screen.
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