A stamp collector wants to magnify an image by 4.0 when the stamp is 3.5 cm from the lens. What focal length is needed for the lens?

In order to heighten your enjoyment of your 29 carat blue diamond, you view it through a lens held close to your right eye at an angular magnification of 5.1. The distance of your right eye's near point is 25 cm.  What is the focal length f of the lens in centimeters? f = ?cm

Two lenses are mounted d = 39 cm apart on an optical bench. The focal length of the first lens is f1 = 9.8 cm and that of the second lens is f2 = 3.1 cm. An object of height ho = 4.9 cm is placed at a distance of do = 24 cm in front of the first lens. Now consider the two-lens system and the final image it forms, i.e., the image created by the second lens. What is the distance, in centimeters, between the object and its final image?  D =?

Is this question set up wrong?  I think the statement "The magnification of a book held 7.50 cm from a 10.0 cm-focal length lens is 3.00." is impossible using the lens equation 1/do + 1/di = 1/f and the equation for magnification m = -di / do.

An object is located 16.6 cm to the left of a diverging lens having a focal length f = −32.4 cm. What is the magnification of the image? Group of answer choices 0.661 2.13 0.346 1.17

A converging lens causes an object 72.7 cm from the lens to create an image 61.7 cm from the lens on the opposite side of the lens. What is the focal length (in cm) of this lens?

You want to purchase a microscope for doing surgeries, which requires that there is at least 10cm distance between the objective lens and the patient. The objective forms a highly magnified real image of the object at a distance L. You want the image to look 50 times larger. What should be focal lengths of the objective and the eye piece assuming L=200mm

An image of the moon is focused onto a screen using a converging lens of focal length f= 35.3 cm. The diameter of the moon is 3.48×106 m, and its mean distance from the earth is 3.85x108 m. What is the diameter of the moon's image? 8.29E-12 m

Mike holds a magnifying glass (convex lens) 5.00 cm above a sheet of paper. He looks at the writing on the page and notices that it is magnified by a factor of 3.00. What is the focal length of the lens he is using? a 2.00 cm b 4.00 cm c 7.50 cm d 3.75 cm

An object is 6 cm in front of a converging lens with a focal length of 10cm. Draw a ray diagram (to scale with a ruler) to find the location of the image. Is the image upright or inverted, and Is the image real or virtual? Then I want to use the thin lens formula to find the image distance and the magnification. I got stuck in the middle of this problem and am confused. Thank you for the help!