Question

So we are using the PhET Geometric Optics simulation to complete these problems. I'm lost on how to find the focal distance that we use for table 1, and I don't know what formulas to use for the table either.

Set the len's refractive index (n) to 1.8 and the radius curvature (R) to .7 m. find the focal distance (f).

Using the focal distance you just found, complete the table.

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

-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 0.7 m. Use the appropriate equation above to solve for the focal distance (f). f the focal distance to confirm your answer.) (Measure Using the focal distance you just found, complete the table below and check your work in the simulation Data Table 1 distance image (di) magnification (m) distance object (do) 120.0 cm 90.0 cm 60.0 cm 30.0 cm 15.0 cm focal distance (f) Repeat the previous exercise, but with a very different lens with the following characteristics: R 80 cm, n 1.25 . Data Table 2 (WATCH YOUR SIGNS!) magnification (m) focal distance (f) distance object (do) distance image (d) 120.0 cm 90.0 cm 60.0 cm 30.0 cm 15.0 cm solve for this first

Answer 1

n = 1.8 R = 0.7m Therefore using lens maker�s formula 1/f = (n - 1) [1/R_1 - 1/R_2] = (n - 1) [1/R - (-1/R)] = 2 (n - 1)/R Therefore f = R/2 (n - 1) = 0.7/2(1.8 - 1) = 0.7/2 times 0.8 = 0.7/1.6 m f = 70/1.6 cm = 4.315 cm Hence using thin tens formula 1/d_i - 1/d_0 = 1/f rightarrow 1/d_i = 1/f + 1/d_0 rightarrow d_i = fd_0/d_0 + f Therefore (i) d_0 = -120 cm Therefore d_i = 4.375 times (-120)/-120 + 4.375 cm d_i = -525/-115.625 = + 4.54 cm Therefore (i) d_0 = -120 cm Therefore d_i = 4.375 times (-120)/- 120 + 4.375 cm d_i = -525/- 115.625 = + 4.54 cm (ii) d_i = 4.375 (-90.0)/-90 + 4.375 cm = -393.75/-85.625 = + 4.6 cm (iii) d_i = 4.375 (-60.0)/-60.0 + 4.375 cm = -262.5/-55.625 = + 4.72 cm (iv) d_i = r.375 (-30.0)/-30 + 4.375 cm = -131.25/-25.625 = + 5.12 cm