Exam 33: Lenses and Optical Instruments

A Keplerian refracting telescope is used to look at craters on the moon.The objective focal length of the telescope is 92 cm and the distance between the objective and eyepiece lenses is 97 cm.The diameter of the objective is 25 cm.What is the focal length of the eyepiece?

A brown newt sits 25 cm from a convex lens having a 12-cm focal length.Which is true of the newt's image?

A bracken fern spore produces an image that is 7.5 cm tall when placed before a converging lens of focal length 6.0 cm.If the spore's true height is 1.5 mm,how far from the lens was its image?

For a diverging lens

Consider a small light bulb,3 m to the left of a biconvex lens,which forms an image 2 m to the right of the lens.The lens is made of glass with index of refraction 1.4 and its two surfaces have equal radii of curvature.How far to the right of the lens would light from the Moon concentrate,if it was incident from the left?

Two lenses are used to create an image of a 15.0-cm tall source that is located 43.0 cm to the left of the first lens,which is a biconcave thin polycarbonate lens (index of refraction n = 1.67)and has a radius of curvature of 25.0 cm for both front and back surfaces.The second lens is 36.0 cm to the right of the first lens.The second lens is a converging lens with a focal length magnitude of 25.0 cm.What is the height of the image?

A telescope has an objective with a focal length of 1200 mm and an eyepiece with a focal length of 0.050 m.What is its angular magnification?

A near-sighted person has an eyeball that is 2.65 cm long.What is the effective power of the optical system (combination of lens and cornea)when viewing objects at his near point (18.0 cm)?

Using ray tracing,find the image of the object (upright arrow)in the system shown having a converging lens where f is a focal point.Which one of the statements is true?

An eye has a near-point at 125 cm.What power contact lens will be needed to move the near-point to 25 cm?

Using ray tracing,find the image of the object (upright arrow)in the system shown having a converging lens where f is a focal point.Which one of the statements is true?

Which of the following statements is false?

For a refracting telescope that uses two converging lenses,it's best to have an eyepiece with

Three converging lenses of focal length 5 cm are arranged with a spacing of 20 cm between them,and are used to image an insect 20 cm away from the first lens.What is the magnification of the image?

A physics student epoxies two converging lenses to the opposite ends of a tube.One lens has a focal length of f₁ = 4.0 cm and the other has a focal length of f₂ = 2.0 cm.She wants to use this device as a microscope.If the desired magnification of this homemade microscope is 80,what length should the student use for the tube?

What would you expect to happen to the magnitude of the power of a lens when it is placed in water (n = 1.33).You may safely assume that the index of refraction for the lens is greater than 1.33.

A Keplerian refracting telescope is used to look at craters on the moon.The objective focal length of the telescope is 92 cm and the distance between the objective and eyepiece lenses is 97 cm.The diameter of the objective is 25 cm.What is the angular magnification of this telescope?