Question

HOLT PHYSICS MODULE 15 Refraction Fill each blank below with the word or phrase that completes the statement. 1. A focuses to a point light rays passing through it. The focusing effect is the result of Light waves are refracted when they pass from one medium to another because their 2. changes. 3-The normal line is an imaginary line- of to the two mediums. Light waves are bent away from the normal or toward it depending on whether the speed of light the second medium. Waves that slow down bend normal, while waves that speed up bend 4. when entering or the the 5. The principal axis passes through theofthe lens at a angle to the plane of the lens. 6. Rays entering the lens parallel to the principal axis are refracted to a single point, called the of the lens to the The focal length is the distance from the 7. Converging lenses are reversible in that they have a on both sides of the lens. 8. is real and When refracted rays converge, the on a ścreen. 9. is virtual and on 10. The image formed by refracted rays that side of the lens as the object. the 11. The focal length for a converging lens is always be positive or negative depending on

Answer 1

Convex lens & its converging property speed perpendicular & boundary increases or decrease & towards & away optical centre & right principal focus optical centre & principal focus principal focus image & on the opposite side of object diverge & same positive & where the object is placed Ray passing through optical centre of a lens does not bend object distance (u) = -5.50 m focal length (f) = + 0.25 m By lens formula: - 1/v - 1/u = 1/f 1/v = 1/u + 1/f = 1/- 5.50 + 1/0.25 \r\n 1/v = -100/550 + 100/25 = -10/55 + 4 = -2/11 + 4 1/v = -2 + 44/11 = 42/11 Rightarrow v = 42/11 m so candle should be placed at a distance 3.81 m from lens on the other side as object u = -30, v = + 60 cm (as real image) 1/v - 1/u = 1/f Rightarrow - 1/60 - 1/(- 30) = 1/f 1/60 + 2/60 = 1/f Rightarrow 3/60 = 1/f Rightarrow f = 20 cm