A magnifier has a magnification of 5×. How far from the lens should an object be placed so that its (virtual) image is at the near-point distance of 25 cm?

A microscope has an objective lens with a focal length of 16.22 mm and an eyepiece with a focal length of 9.06 mm. With the length of the barrel set at 33.0 cm, the diameter of a red blood cell's image subtends an angle of 1.43 mrad with the eye. If the final image distance is 33.0 cm from the eyepiece, what is the actual diameter of the red blood cell? Hint: To solve this equation, go back to basics and use the thin-lens equation. ?m

= A doublet lens consists of two lenses in effective contact. The front lens is biconvex with fi +37.5 cm, and the second is biconcave with f2 = -150 cm. An object of height 2 cm is placed at 80 cm to the left of the combined lens. Calculate the position of the image, and the image height.

Two converging lenses, each of focal length 14.9 cm, are placed 39.6 cm apart, and an object is placed 30.0 cm in front of the first lens. Where is the final image formed? The image is located  cm  ---Location--- in front of the first lens. in front of the second lens. behind the second lens. What is the magnification of the system? M =  ✕

The focal length of a diverging lens is negative. If f = −16 cm for a particular diverging lens, where will the image be formed of an object located 45 cm to the left of the lens on the optical axis? cm to the left of the lensWhat is the magnification of the image?

An object 1.3 cm high is held 3.3 cm from a person’s cornea, and its reflected image is measured to be 0.187 cm high.  (a) Set-up the table for known and unknown quantities. (b) What is the magnification?

People who do very detailed work close up, such as jewellers, often can see objects clearly at much closer distance than the normal 25 cm. (a) What is the power in D of the eyes of a woman who can see an object clearly at a distance of only 7.30 cm? (Assume the lens-to-retina distance is 2.00 cm.)  ____D (b) What is the size in mm of an image of a 6.00 mm object, such as lettering inside a ring, held at this distance? (Include the sign of the value in your answer.)  ______mm (c) What would the size of the image be in mm if the object were held at the normal 25.0 cm distance? (Include the sign of the value in your answer.)  _____mm

The image distance for the lens of a person's eye is2.10 cm.Calculate the focal length of the eye's lens system for anobject (a) at infinity, (b) 500 cm from the eye, and (c) 25 cm from the eye.