Thin Lens Equation

A normal human eye has a focal length of about 0.023 m. If you look at the tip of a pencil, 0.553 m from your eye, how far is the image from the lens of your eye? 

• 0.024 m
• 0.033 m
• 0.045
• 0.055

A converging lens produces an image twice the size of the original. If the object is placed 0.40 m from the lens, and the image produced is 0.80 m from the lens. What is the focal length of the lens? 

• 0.351 m
• 0.267 m
• 0.416 m
• 0.112 m

If the distance of the image from the lens (di) is positive. The image is considered....

• Real 
• Virtual

In the thin lens equation, do represents 

• Distance of the object from the lens
• Distance of the image from the lens

An object .25 m away from a lens produces a focused image on a film .15 m away. What is the focal length of the converging lens?

• 0.094 m

• 0.230 m

• 0.012 m

• 0.032 m

A tree 20 m high is located 40 m from the converging lens of focal length 0.08 m.Calculate the distance from the lens to the image.

• 0.08 m

• 0.01 m

• 0.10 m

• 0.20 m

The d_o will be a _________________ value.

• positive
• negative

The d_i for a real image will be a _________________ value

• positive
• negative

The d_o can be a negative value.

• True
• False

The d_i for a virtual image will have a ______ value.

• positive
• negative