Exam 23: Mirrors and Lenses

A farsighted boy has a near point at 2.3 m and requires contact lenses to correct his vision to the normal near point.What is the correct choice of lens power for the contact lenses?

You have a choice between two lenses of focal lengths f_a and f_b,where f_b = 2f_a,to use as the objective lens in building a compound microscope.If the magnification you obtain using lens a is M_a,what will be the magnification when using lens b?

An object is placed 60 cm from a convex lens with a focal length of magnitude 10 cm.What is the magnification?

What power contact lens should be used to correct the vision of a farsighted person whose near point is 80 cm so she can see things clearly that are 25 cm in front of her?

The near point of a farsighted person is 65 cm.What power contact lens must he use to correct this problem and be able to read a book at a normal near point of 25 cm?

A lighted candle is placed a short distance from a plane mirror,as shown in the figure.At which location will the image of the flame appear to be located?

You have available lenses of focal lengths 2.0 cm,4.0 cm,8.0 cm,and 16 cm.If you could use any two of these lenses to build a telescope,what is the lens separation for the telescope to provide the maximum magnification for comfortable viewing of a planet?

A stature that is 3.0 cm tall statue is 24 cm in front of a concave mirror.The magnitude of the radius of curvature of the mirror is 20 cm. (a)Is the image real or virtual? (b)How far is the image from the mirror? (c)Is the image upright or inverted? (d)How tall is the image?

A refracting telescope has an eyepiece of focal length -80 mm and an objective of focal length 36 cm.What is the magnification of this instrument?

The focal lengths of the objective lens and the eyepiece of a microscope are 0.50 cm and 2.0 cm,respectively,and their separation adjusted for minimum eyestrain is 6.0 cm.If the microscope is focused on a small object,what is the distance between the object and the objective lens?

A compound microscope consists of an objective lens of focal length f₀ and an eyepiece that by itself produces an angular magnification 25.0.The microscope is designed so that the object to be viewed is on the left side of the objective lens and is focused in a plane that is 28.00 cm away from the right-hand (or inside)focal point of the objective lens.When properly adjusted,the eyepiece and the objective lens are 29.90 cm apart.The eyepiece magnification is based on an image at infinity and a near point at 25.0 cm.What is f₀?

You are given two converging lenses to build a compound microscope.Lens A has focal length 0.50 cm and lens B has focal length of 3.0 cm.Which one of the two lenses would you use for the objective?

For relaxed viewing with a microscope or a telescope,the eyepiece is adjusted to place the image at

The length of a telescope is 1.60 m and it has a magnification of 60.0.What is the focal length of the eyepiece?

A nearsighted person wears contact lenses having a power of -0.15 diopters.What is the person's uncorrected far point?

Which one of the following is a characteristic of a compound microscope?

The objective lens and the eyepiece of a microscope have focal lengths of 4.0 mm and 25 mm,respectively.The objective produces a real image 30 times the size of the object,with the final image viewed at infinity.The near point of the microscope user is at 25 cm.What is the magnitude of the overall magnification of the microscope?

The focal length of the objective lens of a telescope is 75.0 cm,and the eyepiece has a focal length of 6.00 cm.What is the magnification of this telescope?

Cal is viewing the Moon with his new telescope,using a 10-mm focal length eyepiece.For greater detail,he wishes to double the magnification of his telescope.An eyepiece having which one of the following characteristics will accomplish this for him?

A person cannot see clearly objects more than 70.0 cm away.What power of corrective lens should be prescribed if the glass is to be worn 1.00 cm in front of the eye?