Exam 27: Optical Instruments

A person having a near point of 25 cm uses a magnifying glass with a focal length of 10 cm.What is the angular magnification of the glass for that person when her eyes are focused at infinity?

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?

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?

Which of the following statements are correct? (There could be more than one correct choice. )

A myopic (nearsighted)child wears contact lenses that allow her to have clear distant vision.The power of the lenses of her eyeglasses is -3.00 diopters.Without the corrective lenses,what is the far point of the girl?

The length of a telescope is 2.20 m and the focal length of the eyepiece is 1.9 cm.What is the focal length of the objective lens?

A student constructs an astronomical telescope with a magnification of 10.If the telescope has an objective lens of focal length 0.50 m,what is the resulting length of the telescope?

A compound microscope has an objective with a focal length of 3.00 mm and an eyepiece of focal length 6.00 cm.It is adjusted for minimum eyestrain for persons with a near point of 25 cm.If the two lenses are separated by 40.0 cm,what is the total overall magnification?

Which one of the following statements is correct?

A compound microscope has a 18-cm-long barrel and an objective lens with a focal length of 8.0 mm.What is the focal length of the eyepiece to give a total magnification of 240? It is adjusted for minimum eyestrain for persons with a near point of 25 cm.

Mahmood is farsighted and cannot see objects clearly that are closer to his eye than 80.0 cm.What is the focal length of the contact lenses that will enable him to comfortably see objects at a distance of 25.0 cm from his eyes?

The distance between the object to be viewed and the eyepiece of a compound microscope is 18.0 cm.The focal length of its objective lens is 0.80 cm and the eyepiece has a focal length of 2.3 cm.The near-point distance of the person using the microscope is 25.0 cm.What is the magnitude of the total magnification of the microscope if it is designed for minimum eyestrain?

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?

A microscope has an objective lens of focal length 1.40 mm and an eyepiece of focal length 20.00 mm.It is adjusted for minimum eyestrain for persons with a near point of 25.0 cm.A blood sample is placed 1.50 mm from the objective.The magnitude of the overall magnification is closest to

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 refracting telescope.If the magnification you obtain using lens a is M_a,what will be the magnification when using lens b?

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 person uses a converging lens of focal length 5.0 cm as a magnifying glass.What is the angular magnification if the person's eye is relaxed and has a near point of 25 cm?

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 distance between the object and the focal point of the objective lens?

If the lens in a person's eye is too highly curved,this person is suffering from

A 35-mm camera equipped with a 40-mm focal length lens is used to photograph a tree 17 m tall.If a 32-mm high image of the tree on the CCD sensor is required,how far should the camera lens be from the tree?