15. An object is placed 70.0 cm in front of a lens whose focal length is +23.0 cm. The image that is formed of this object will be: a) inverted and 2.04 times the size of the object. b) inverted and 0.489 times the size of the object. c) erect and 2.04 times the size of the object. d) erect and has the same size as the object. e) erect and 0.489 times the size of the object.

A contact lens is made of plastic with an index of refraction of 1.54. The lens has an outer radius of curvature of +1.95 cm and an inner radius of curvature of +2.47 cm. What is the focal length of the lens? cm Need Help? Read It Watch It

4. An object with a height of h = 9.00 cm is placed a distance of s, = 28.0 cm in front of a concave mirror with a focal length of f = 10.2 cm. A convex refracting surface is located a distance of L = 39.4 cm in front of the mirror as shown. The refracting surface has a radius of R = 7.05 cm and an index of refraction of n = 1.91. The mirror and refracting surfaces are surrounded by air. Where will the refracting surface form a secondary image from the image created by the mirror? What is the height and type of this image? object optical axis

1. A dentist examines the cavity in a person's tooth using a concave mirror of focal length +2.0 cm. If the cavity is 1.5cm from the mirror's surface, (a) where is the image located, (b) is it real or virtual, and @ what is its size? 2. The observation mirror in a store is a convex mirror and has a focal length of -2m. Calculate (a) the image location and (b) the image height of a 1.5 m-tall boy standing 4.0 m from the mirror. 3. A 1.6 m-tall man stands in front of a plane mirror, How tall is the image form? Useful formulae: where: = 1/d, + 1/d, f- focal length do- distance of object from mirror di- distance of image from h'- size/height of image h- size/height of object h' = -hd,/d.

An image is located 346 mm behind a 204 mm focal length lens. A) Find the object distance. B) Find the magnification of the image. C) Is the image upright or inverted? factor of 4 or when you place it 8.0 cm behind a lens the

20. This question is about convex lenses. (a) A convex (converging) lens is u d to project an image onto a screen. The focal length of the lens is 10 cm. The object is placed at a distance of 15 cm from the centre of the lens on the principal axis. (i) Define principal axis. (ii) Construct rays to locate the position of the image. 15 cm object principal axis f f 10 cm 10 cm convex lens (iii) Identify the nature of the image.

2. An object is placed 50.cm in front of a converging lens and then 15.5cm in front of a diverging lens. Both lenses have a focal length of 12.0cm. For both cases, find the image distance.

Problem 96. Indicate the single lens type (converging or diverging) and object position that will lead to the following kind of images. If no single lens system can produce the particular image indicate that this is so. A) real, upright, enlarged image. B) huge image at "infinity". C) real, enlarged, inverted image. D) tiny inverted image very near the focal point. E) real, reduced in size, inverted image. F) virtual, reduced in size, upright image. G) virtual, enlarged, upright image. H) real, inverted image that is the same size as the object. I) virtual, enlarged, inverted image. Problem 97. You are handed a converging lens and you have a ruler. Describe two different simple ways to determine the focal length of this lens. Each way should involve making only one measurement.

15. An object is placed at a distance xo =-1.5f in front of a convex lens of focal length f located at x = 0. An identical object is placed at a distance x'o = -2f in front of a concave lens of focal length - f located at x' = 0. Find the difference between the two image positions (x' - Xi). Draw ray diagrams.

45. You have been provided with a concave spherical mirror with focal length 20 cm. Calculate the image distance and magnification when a 14 cm high object is placed at a distance 35 cm in front of the mirror. Will the image be real or virtual? Inverted or erect? What would be the difference in image formation for the object distance 20 cm and 10 cm?