# Worksheet: The Simple Magnifier

In this worksheet, we will practice defining the angular magnification of images produced by simple magnifiers and correlating this to their focal lengths.

Q1:

You view a mountain with a magnifying glass of focal length cm. What is the magnification?

• A3.4x
• B2.9x
• C3.7x
• D4.0x
• E2.5x

Q2:

What will be the angular magnification of a convex lens with the focal length 2.5 cm?

• A10x
• B13x
• C11x
• D15x
• E16x

Q3:

If the image formed on the retina subtends an angle of and the object subtends an angle of , what is the magnification of the image?

• A
• B
• C
• D
• E

Q4:

How far should you hold a magnifying glass of focal length 2.1 cm from an object to obtain a magnification of ? Assume you place your eye 5.0 cm from the magnifying glass.

Q5:

A magnifying glass produces an angular magnification of 4.5x when used by a person with a near point of 18 cm. What is the maximum angular magnification obtained with the lens by a person with a near point of 45 cm?

• A9.8x
• B8.8x
• C8.5x
• D9.5x
• E9.3x

Q6:

A magnifying glass forms an image 10 cm on the opposite side of the lens from the object, which is 10 cm away. What is the magnification of this lens for a person with a normal near point if their eye 12 cm from the object? The lens-to-retina distance is 2.00 cm.

• Ax
• Bx
• Cx
• Dx
• Ex

Q7:

A doctor examines a mole with a 10.0 cm focal length magnifying glass, which is held 12 cm from the mole. What magnification does the lens produce?

Q8:

An object viewed with the naked eye subtends a angle. If you view the object through a 10x magnifying glass, what angle is subtended by the image formed on your retina?

Q9:

A magnifying lens with a focal length of 14.0 cm is held 4.00 cm from an eye and the object is 13.0 cm from the eye. What is the magnification of the lens?

• A8.33x
• B12.3x
• C9.25x
• D10.7x
• E7.00x

Q10:

Find the angular magnification of an image by a magnifying glass of if the object is placed from the lens and the lens is close to the eye.

Q11:

A magnifying glass produces a magnification of 4.00 when held at a distance of 6.00 cm from a coin. What is the focal length of the magnifying glass?

Q12:

What is the angular magnifier of a binocular that has a focal length of 1.9 cm for the eyepiece and a focal length of 9.0 cm for the objective?

Q13:

You view an object by holding a 3.50 cm focal length magnifying glass 10.0 cm away from it. How far from your eye should you hold the magnifying glass to obtain a magnification of 10.0x?

Q14:

While outdoors on a sunny day, a student holds a large convex lens of radius 5.0 cm vertically above a sheet of paper, producing a bright spot of light on the paper 2.0 cm in radius. The magnitude of the electric field within the bright spot of light is and that of the sunlight leaving the side of the lens facing the paper is . Find the ratio of to .

Q15:

The normal power for distant vision is 50.0 D. A young woman with normal distant vision can increase the power of her eyes by 13.0% by using accommodation. What is the power increase of her accommodated eyes?