A 2.0-cm-diameter spider is 2.0 m from a wall. Determine the focal length and position (measured from the wall) of a lens that will make a half-size image of the spider on the wall.

In order to start a fire, a camper turns a lens toward the sun to focus its rays on a piece of wood. The lens has a 10 cm focal length. Draw a ray diagram of the lens and the incoming light rays to show where the wood should be placed for the best effect.

A 2.1-cm-tall object is 30 cm to the left of a lens with a focal length of 15 cm. A second lens with a focal length of -5 cm is 45 cm to the right of the first lens. Calculate the distance between the first image and the second lens. Calculate the image height.

Q1 a) The eyepiece of a refracting telescope has a focal length of 9.00cm. The distance between objective and eyepiece is 1.80m, and the final image is at infinity. What is the angular magnification of the telescope? F=580×10² 14

The distance between the lenses in a compound microscope is 18 cm. The focal length of the objective is 1.5 cm. If the microscope is to provide an angular magnification of - 68 when used by a person with a normal near point (25 cm from the eye), what must be the focal length of the eyepiece?

A person with a normal near point (25 cm) using a compound microscope with objective of focal length 8.0 mm and an eyepiece of focal length 2.5cm can bring an object placed at 9.0mm from the objective in sharp focus. What is the separation between the two lenses? Calculate the magnifying power of the microscope,