The purpose of this lab is to investigate basic optics systems, examining the relationship between image position, size and lens focal lengths.

Part A: General Observations

1. Position the light source at x = 0 cm, with the circle and arrows of the light source facing along the track. Place the screen at x = 100 cm. Starting right in front of the screen, move the +200 mm lens slowly along the track toward the light source. Describe in detail what you observe.









2. Repeat question 1 using the +100 mm lens instead of the +200 mm lens.









3. Now place the screen at 50 cm. Flip the light source by 180 degrees so the slits and colors are pointed along the track and just hit the top of the screen. Arrange the slide on the light source so only the three colors hit the screen. Place the +100 mm lens at x = 20 cm and tilt the light source down slowly so colors can be seen on the screen that have passed both over the top of the lens and through it. Describe what you see.






4. Describe what happens as the lens is slid closer to the screen.







5. How far from the screen is the lens when the colors merge to one? What color do they make?




What do you notice when you use a pen to cover just the blue slit at the light source?

When you cover just the red slit?

When you cover just the green slit?

6. Remove the +100 mm lens from the track. Slide the slide on the light source to get five lines of white light appearing on the screen. Place the +100 mm lens back on the track close to the light source and move it toward the screen slowly. Describe what you see.







7. How far from the screen is the lens when the lines merge into one?



8. PREDICT where you should place the +200 mm lens to make the three colors become one.



9. MEASURE precisely where the +200 mm lens must be placed to best merge the colors to one.



Part B: Conclusions

10. What do the numbers written on the lenses mean? Are they accurate?