A magnifying glass has a convex lens of focal length 15 cm. At what distance from a postage stamp should you hold this lens to get a magnification of +2.0?
[Ques. 2] Short-period comets, such as Halley's Comet, are believed to come from the ______________.
Fill in the blank(s) with correct word
[Ques. 3] Voltage has the units of ______________, which is called a volt.
Fill in the blank(s) with correct word
[Ques. 4] An object is placed 25 cm in front of a lens of focal length 20 cm. 60 cm past the first lens is a second lens of focal length 25 cm. How far past the 25 cm lens does the final image form?
a. 20 cm
b. 40 cm
c. 16 cm
d. 25 cm
e. 47 cm
[Ques. 5] Long-period comets are believed to come from the ______________.
Fill in the blank(s) with correct word
[Ques. 6] Another name for electric potential difference is ______________.
Fill in the blank(s) with correct word
[Ques. 7] A fish is 80 cm below the surface of a pond. What is the apparent depth (in cm) when viewed from a position almost directly above the fish? (For water, n = 1.33.)
a. 50
b. 60
c. 40
d. 70
e. 110
[Ques. 8] Sunlight reflected from interplanetary dust results in the appearance of ______________.
Fill in the blank(s) with correct word
[Ques. 9] In a(n) ______________, electrons do not move freely.
Fill in the blank(s) with correct word
[Ques. 10] A girl is sitting on the edge of a pier with her legs dangling over the water. Her soles are 80.0 cm above the surface of the water. A boy in the water looks up at her feet and wants to touch them with a reed. (nwater = 1.333.) He will see her soles as being
a. right at the water surface.
b. 53.3 cm above the water surface.
c. exactly 80.0 cm above the water surface.
d. 107 cm above the water surface.
e. an infinite distance above the water surface.
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