PHY 2020 Lecture Notes - Lecture 25: Thin Lens, Focal Length, Sign Convention
Document Summary
Using trigonometry and law of refraction, we have: na/s + nb/s" = nb-na/ r. If the center of curvature is on the outgoing side of the surface, then r>0. A spherical fish bowl: a small tropical fish is at the center of a water-filled, spherical fish bowl 28. 0 cm in diameter. (a) find the apparent position and magnification of the fish to an observer outside the bowl. Is the focal point actually within the pool? (a) na/s + nb/s"= nb-na/r. m= nas"/ nbs. Light comes from the fish to the person"s eye: r= -14. 0 cm. s= +14. 0 cm. Nb= 1. 00 (air: 1. 333/ 14. 0 cm + 1. 00/s"= 1. 00-1. 333/ -14. 0 cm. s"= -14. 0 cm, m= -(1. 333)(-14. 0 cm)/ (1. 00) (14. 0 cm)= +1. 33. The focal point is outside the bowl and there is no danger to the fish. Note: the rays refract when they exit the bowl back into the air so the image, we calculated is not the final image.
