Chapter 11 Review Mirrors & Lenses

What is an angle of incidence? 2 The angle between an incident ray and the normal of an optical device. Category: Reflection

What is the difference in shape between a convex and a concave lens? 3 A convex lens is thicker whereas a concave lens is thinner in the middle than at the outside edges. Category: Lenses

What is an optical device? Give three examples. An optical device is a device that produces an image of an object. Examples: camera, LCD projector, overhead projector, magnifying glass, glasses, eyes, telescopes, microscopes, movie projectors, etc. Category: Images

What is the principal axis of a curved mirror? 5 A line through the centre of the mirror that includes the focal point (principal focus). Category: Mirrors

Describe the size, attitude, location, and type of image you get in a plane mirror 6 The image is the same size as the object, upright, behind the mirror, and is virtual. Category: Mirrors

image? What is a virtual image? 7 An image that cannot be placed on a screen and can only be seen by looking at or through an optical device (light rays diverge from the optical device). Category: Images

Why does an image appear behind a plane mirror? 8 Rays reflecting off a plane mirror diverge. It you extend these reflected rays back, they would converge behind the mirror. Category: Mirrors

If an incident ray is at an angle of 20 degrees from the surface of a mirror (not from the normal), what will be the angle of reflection? 9 If the incident ray is at an angle of 20 degrees from the mirror, then the angle of incidence is 90 – 20 = 70 degrees, so the angle of reflection is also 70 degrees. Category: Reflection

In what situation would a light ray passing through a lens not refract at all? 10 When a light ray hits a lens at 90 degrees (along it’s normal or principal axis), it will not refract. Category: Lenses

Describe the size, attitude, location, and type of image obtained by holding an object very far beyond the focal point of a concave mirror. 11 The image is smaller than the object, inverted, in front of the mirror, and real. Category: Mirrors

What type of mirror is a cosmetic mirror and why does a person have to be close to it for it to be useful? Concave. The person must be within the focal point in order to get a larger (magnified) image. Category: Mirrors

How is a convex lens similar to a concave mirror? 13 Category: Lenses They both cause light rays to converge at a focal point. They also form similar images in terms of size, attitude, and type depending on how far away the object is from the lens or mirror.

Give two examples of ways to diffuse light in a room so that it is easier on the eyes. 14 Using frosted light bulbs, irregular surfaces on ceilings (such as stucco), using lampshades, avoiding too many mirrors or direct light sources. Category: Reflection

Describe the size, attitude, location, and type of image obtained by holding an object just beyond the focal point of a concave mirror. 15 The image is larger than the object, inverted, in front of the mirror, and real. Category: Mirrors

What is diffuse reflection? 16 The reflection of light off an irregular surface so that it scatters in many directions and an image is not formed. Category: Reflection

Does a light ray speed up or slow down as it passes from air to water? Does it bend away from or towards the normal? 17 The light ray slows down and bends towards the normal. Category: Refraction

Why does the passenger side-view mirror of a car read “Objects in mirror are closer than they appear”? 18 A side-view mirror is a convex mirror, used because it gives a wide side view. The image in a convex mirror is always smaller, giving the illusion that an object is farther away than it really is. Category: Mirrors

How would you describe the reflected rays from a convex mirror? 19 Category: Mirrors Diverging (they spread apart).

What is a real image? 20 An image that can be placed on a screen at that can be seen without looking at or through an optical device (light rays converge from the optical device). Category: Images

How would you describe the reflected rays from a concave mirror? 21 Converging (they come together). Category: Mirrors

What is specular reflection? 22 The reflection of light off a smooth, shiny (regular) surface so that an image is formed. Category: Reflection

What is refraction? 23 Category: Refraction The bending of light as it passes from one material to another (due to a change in speed).

What type of mirror is used in a flashlight and why? 24 A concave mirror is used because it reflects the light rays from the bulb into a concentrated, parallel beam. Category: Mirrors

In what situation would a concave mirror produce an upright, virtual image? 25 When the object is within the focal point of the mirror (i.e. it is very close to the mirror). Category: Mirrors

What is a lens? 26 A curved, transparent device that causes light to refract as it passes through. It produces an image of an object. Category: Lenses

What is the difference between an incident ray and a reflected ray? 27 An incident ray is a ray of light that travels towards a reflecting surface, whereas a reflected ray bounces off a reflecting surface. Category: Reflection

What type of mirror is a surveillance mirror? Why? 28 It is a convex mirror because it reflects light rays from all parts of a room towards a person’s eyes, thus giving a wide view. Category: Mirrors

Describe the size, attitude, location, and type of image obtained by holding an object in front of a convex mirror. 29 The image is smaller, upright, behind the mirror, and virtual. Category: Mirrors

How would you describe light rays passing through a convex lens? 30 They converge (come together). Category: Lenses

Describe why the straw appears bent in the glass of water. 31 The light rays coming from the part of the straw that is under water change speed and direction as they pass from water to air towards your eyes. This makes them appear to come from a place under the water where the straw actually isn’t, so the straw appears bent. Category: Refraction

What is the difference in shape between a concave and a convex mirror? 32 A concave mirror is one that curves inwards (the reflecting surface is on the inside curve). A convex mirror curves outwards (the reflecting surface is on the outside curve). Category: Mirrors

Describe the size, attitude, and type of image produced by a concave lens. 33 The image is smaller, upright, and virtual. Category: Lenses

Give two examples of specular reflection. 34 Light reflecting off a mirror, shiny metal, the surface of still water, etc. Category: Reflection

What type of lens does a magnifying glass use? Why must you hold the object you are observing close to the lens? 35 Convex lens. You must have the object within the focal point in order for its image to be enlarged (magnified). Category: Lenses

Name three devices that use lenses. 36 Category: Lenses Camera, LCD projector, glasses, contacts, magnifying glass, microscope, eyes, etc.

Describe the size, attitude, location, and type of image obtained by holding an object within the focal point of a concave mirror. 37 The image is larger, upright, behind the mirror, and virtual. Category: Mirrors

What is the focal length of a curved mirror? 38 The horizontal distance between the focal point and the middle of the mirror. Category: Mirrors

What happens to parallel light rays that strike a concave lens? 39 They diverge (spread apart). Category: Lenses

What is the focal point of a concave mirror? 40 The point at which all incident parallel light rays are reflected through (where they converge after being reflected). Category: Mirrors

What are the two laws of reflection? The angle of incidence equals the angle of reflection. 2. The incident ray, normal, and reflected ray all lie in the same plane. Category: Reflection