Question

Phys1011: Geometrical Optics Exploration :i have these labs without any text book or handouts assigned. i would love some insight and help so that i can learn the concepts better and prep for tests thru this.

Introduction:

In this lab, you will investigate lens optics using the 3-ray system (parallel-focal, focal-parallel, central). Remember, the real focal point of a lens is behind the lens. The lens we will use in this simulation is a thin double-convex lens.

You will then run a series of small trials with the real lenses included in the lab.

where f is the focal length, d₀ is the object distance, d_i is the image distance, n is the index of refraction, R is radius of curvature, m is the magnification, h_i is the image height, and h₀ is the object height.

Part 1. Geometric Optics Ray Tracing Model

Procedure: Open the PHeT simulation at https://phet.colorado.edu/sims/geometric-optics/geometric-optics_en.html. Take some time and familiarize yourself with the simulation. You are able to move the object and the lens and change the characteristics of the lens. During this lab, be sure to always anchor your image on the principal axis (horizontal blue line). The pencil’s eraser works well for this. Click Principle rays to draw the rays using the 3-ray system that we are familiar with from our textbook.

1. Move the object towards the lens. What happens to the image formed on the other side of the lens as the object is moved closer to the lens?

2. As you move the object inside the lens’ focal point something odd happens. Rays that don’t meet diverge. Does this mean no image will be formed? Where is the image? Click on “Virtual Image.” Explain how a real image and a virtual image are different.

3. Click on the ruler. You will need to make several measurements during the lab. You may, if you wish, leave your measurements in cm when using the formulas given above. Set the lens’s refractive index (n) to 1.8 and the radius of curvature (R) to 0.7m. Use the appropriate equation above to solve for the focal distance (f).
f = _____________    (Measure the focal distance to confirm your answer.) Using the focal distance you just found, complete the table below and check your work in the simulation.

          focal distance (f)                              distance object (d_o)                        distance image (d_i)                            magnification (m)

	120. cm
	90. cm
	60. cm
	30. cm

4. Repeat the previous exercise, but with a very different lens with the following characteristics: : R = 80cm, n = 1.25

WATCH YOUR SIGNS   Real image d_i should be (circle: positive or negative)
while virtual images d_i should be (circle: positive or negative)

    focal distance (f)                                    distance object (d_o)                        distance image (d_i)                            magnification (m)

solve for this first	120. cm
	90. cm
	60. cm
	30. cm

Model Conclusion Questions and Calculations:                    

5.     Images found behind a double-convex lens are real / virtual images that will be upright / inverted.

6.     As the radius of curvature of the lens increases, the focal point of that lens becomes closer to / further away from that lens.

7.     As the refractive index of the lens increases, the focal point of that lens becomes closer to / further away from that lens.

Answer 1

1) As the object is moved towards the lens, the image is moving away from the lens and is getting magnified in size.

2)When the object lies inside the lens focal point, the rays are diverging. Image is formed and it is a virtual image . If an image is real , it forms on the other side of lens. And a virtual image is formed on the same side as the obect.

3) Focal length

and   

From the Phet simulation ,

Focal distance (cm)	Object distance d0 (cm)	Image distance di (cm)	Magnification m
44	120	68	-0.57
44	90	84	-0.93
44	60	154	-2.57
44	30	-80	2.68

4)

and   

From the Phet simulation ,

Focal distance (cm)	Object distance d0 (cm)	Image distance di (cm)	Magnification m
160	120	- not visible	-
160	90	-206	2.29
160	60	-96	1.60
160	30	-37	1.23

5)Images found behind a double convex lens are real and inverted.

6) As the radius of curvature of the lens increases, the focal point of that lens moves further away from that lens.

7) As the refractive index of the lens increass, the focal point of that lens becomes closer to that lens.