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1. An object 6 cm from a lens of focal length 4 cm projects a real image. What i

ID: 2270048 • Letter: 1

Question

1. An object 6 cm from a lens of focal length 4 cm projects a real image. What is the image distance from the lens? 2. A 16 microcurie of radio iodine with a half-life of 8 days is administered to a patient for diagnostic purposes. If the biological half-life is two days, what activity is microcurie is left after 8 days? 3. The half life of radiogold is 2.8 days. If you started with 2 grams of it, how much would be left after 14 days? 1. An object 6 cm from a lens of focal length 4 cm projects a real image. What is the image distance from the lens? 2. A 16 microcurie of radio iodine with a half-life of 8 days is administered to a patient for diagnostic purposes. If the biological half-life is two days, what activity is microcurie is left after 8 days? 3. The half life of radiogold is 2.8 days. If you started with 2 grams of it, how much would be left after 14 days? A 16 microcurie of radio iodine with a half-life of 8 days is administered to a patient for diagnostic purposes. If the biological half-life is two days, what activity is microcurie is left after 8 days? 3. The half life of radiogold is 2.8 days. If you started with 2 grams of it, how much would be left after 14 days? The half life of radiogold is 2.8 days. If you started with 2 grams of it, how much would be left after 14 days?

Explanation / Answer

1) i/f = i/v - i/u

=> 1/4 = 1/v - (1/-6)

=> 1/v = 1/4 - 1/6 = 2/24 = 1/12 => v = 12 cm to the opposite side of object.


2) 8 days is 4 half lives => 16/(2)^4 = 1 microcurie


3) 14 days is 5 half-lives.

So, 2/(2)^5 = 2/32 = 0.0625 grams