These count 4 points each, or 44 total. P2 (a phrase is sufficient), P7 (write a sentence or two), P9 (write a sentence or two), P11, P12 (write sentences), P13 (you may find it easier to answer if you use a drawing like the one above PH3 on p. 206), The dark region creates less lateral inhibition in the region it is next to. Hence the lighter region next to the darker region appears even lighter. P17a (but not 17b or 17c)) for both scotopic and photopic vision. About 20 images per second. (Optional: This applies to low light levels. At higher light levels, it is 50 per second.)These additional questions require the cardboard telescope made in class. P101. (A) Slide the two cardboard tubes apart so that the telescope is in two pieces. Point the larger tube with the objective lens at the sun with the lens toward the sun. The light from the sun will focus to a point at a short distance beyond the open end of the tube. Find this point by moving a piece of paper around near the focal point. What is the focal length of the lens (the distance from the lens to the focal point)? Please give your answers in centimeters. Answer: about 40 cm, but any answer 30 to 50 cm will do. (B) The eyepiece has a much shorter focal length. Point the open end of the smaller tube (that has the eyepiece lens) toward the sun with the lens at the end away from the sun. Find the focal point with a piece of paper. Measure the focal length in centimeters, which will be the distance from the lens to the focal point. Don't measure from the piece of foam. Expect an answer that is a few centimeters. If you have problems with the eyepiece in the foam, you can take the eyepiece lens out of the telescope to find the focal length. Answer: about 2.5 cm (an inch), but answers from 2 to 3 cm will to. P102. Divide the focal lengths of the lenses to determine the magnification of the telescope. Answer: Magnification = 40/2.5 = 16, but numbers from 10 to 20 will do. P103. Estimate the magnification of the telescope by observing an object. For example, observe the moon. Rest your elbows on a car roof or some other object so that it is easier to hold the telescope still. With both eyes open, compare the size seen through the telescope to the size seen with the unaided eye. If the moon is not visible, use a distant building or an automobile license plate. Answer: numbers from 4 to 20 are OK. P104. Focus the telescope on a distant object, like a telephone pole or mountain top. Then focus the telescope on an object about 10 feet away. To get the nearer object in focus, did you move the eyepiece closer to the objective lens or further away from it? Answer: for nearby objects, the eyepiece will be further away from the
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