Investigation of Lens Simulation

Lens simulation Investigation

Go to http://www.colorado.edu/physics/phet,where you will find the Geometric Opticsactivity under “Light & Radiation.” Take the pencil and raise it so that the eraser is sitting on the principal axis. Click on the “principalrays” button.

1.1 Draw the ray diagram. Describe the three special principal rays:how do they enter the lens, and how do they exit the lens?

1.2 There are several properties of the lens youcan change in this simulation. For eachone below, PREDICT what you thinkthe effect will be on the image (its size, location, and brightness), then give the actual answer:

a) Radius of curvature of the lens

b) Refractive index

c) Diameter

1.3 You can change the location of your object(the pencil). Drag the pencil so that itis farther away from the lens. Explain the result.

1.4 Drag the pencil so the eraser is right on topof the focus. Draw the ray diagram. A) What happens to the two principal raysthat enter the lens? B) Will they everform an image?

2. Get a magnifying lens and use it tolook at this paper.

2.1 How do you use the lens to make the words appear larger? Find the spot where the magnification ishighest and explain in terms of the focal length of the lens.

2.2 Sketch a ray diagram of how you think the magnifying lens might work.

2.3 Now back to the sim: drag the pencil so it isinside the focus. Draw the raydiagram. A) Will the rays ever form animage, and if so, where? Click on“virtual image” to check your answer. B)Imagine that you are looking through the lens from the righthand side. What would you see? Use your answer, and your drawing, to explainhow a magnifying lens works