Chapter 19: Optics 19.1 Mirrors

The Law of Reflection The law of reflection states that the angle of reflection is equal to the angle of incidence.

The Law of Reflection The angle of incidence is the angle the incident ray makes with a line drawn perpendicular to the surface of the mirror. The angle of reflection is the angle the reflected ray makes with the perpendicular line.

The Law of Reflection The study of optics assumes that light is made up of rays that travel in straight lines. A ray diagram shows how rays change direction when they strike mirrors and pass through lenses.

The Law of Reflection Incident ray The flat (plane) mirror and the mirror-like lake surface both obey the law of reflection. Angle of incidence Angle of refraction Refracted ray

A plane mirror always produces a virtual image. Plane Mirrors A plane mirror always produces a virtual image.

Plane Mirrors A virtual image is a copy of an object formed at the location from which the light rays appear to come. When you look into a plane mirror, you see your reversed reflection—a right-left reversed image of yourself.

Concave mirrors can form either real or virtual images. Concave and Convex Mirrors Concave mirrors can form either real or virtual images. Convex mirrors always cause light rays to spread out and can only form virtual images.

Concave Mirrors When the inside surface of a curved mirror is the reflecting surface, the mirror is a concave mirror. The curvature of the reflecting surface causes the rays to come together. The point at which the light rays meet is called the focal point.

Concave and Convex Mirrors The type of image formed depends upon where the object is in relation to a concave mirror. When object is farther from the mirror than focal point, reflected rays meet in front of the mirror to form a real image.

A real image is a copy of an object formed at the point where light rays actually meet. Unlike a virtual image, a real image can be viewed on a surface such as a screen.

When the outside surface of a curved mirror is the reflecting surface, the mirror is a convex mirror. The curvature of the convex mirror causes the reflected rays to spread out. The image formed by a convex mirror is always upright and smaller than the object. Convex mirrors can only form virtual images.

Mirror Connection Archimedes is said to have burned the entire Roman fleet by focusing the rays of the sun with a huge curved mirror. Explain if this is possible and what type of mirror it would have been.

The image in a plane mirror appears to be in front of the mirror. Assessment Questions The image in a plane mirror appears to be in front of the mirror. behind the mirror. in the plane of the mirror. perpendicular to the plane of the mirror.

The image in a plane mirror appears to be in front of the mirror. Assessment Questions The image in a plane mirror appears to be in front of the mirror. behind the mirror. in the plane of the mirror. perpendicular to the plane of the mirror.

A real image formed by a mirror is always right-side up. Assessment Questions A real image formed by a mirror is always right-side up. always smaller than the object. able to be projected on a screen. only formed by convex mirrors.

A real image formed by a mirror is always right-side up. Assessment Questions A real image formed by a mirror is always right-side up. always smaller than the object. able to be projected on a screen. only formed by convex mirrors.

An image of an object, formed by a convex mirror, is always Assessment Questions An image of an object, formed by a convex mirror, is always upright and smaller than the object. upside down and smaller than the object. upright and larger than the object. upside down and larger than the object.

An image of an object, formed by a convex mirror, is always Assessment Questions An image of an object, formed by a convex mirror, is always upright and smaller than the object. upside down and smaller than the object. upright and larger than the object. upside down and larger than the object.

Assessment Questions 4. According to the law of reflection, the angle of reflection is equal to the angle of incidence. True False

Chapter 19: Optics 19.2 Lenses

Convex lenses form either real or virtual images. Concave and Convex Lenses Concave lenses always cause light rays to spread out and can only form virtual images. Convex lenses form either real or virtual images.

Concave Lenses A lens is an object made of transparent material that has one or two curved surfaces that can refract light. A concave lens is curved inward at the center and is thickest at the outside edges.

The rays enter the lens at different angles, and so they emerge from the lens at different angles. Concave lenses cause incoming parallel rays to spread out, or diverge. A concave lens forms a virtual image (always smaller than the object).

A convex lens is curved outward at the center and is thinnest at the outer edges. As the rays pass through the lens, each one is refracted, and they emerge at different angles. Convex lenses cause incoming parallel rays to come together, or converge.

Concave and Convex Lenses The converging rays meet at the focal point, on the side of the lens opposite to the object. Whether an image is real or virtual depends upon how far the object is from the lens.

Lens Question A magnifying glass is a simple lens. Explain what type of lens can be used as a magnifying glass and draw a diagram showing how light rays would be bent.

Light refracts when it passes from air to water because Assessment Questions Light refracts when it passes from air to water because the wavelength is different in the two media. the frequency is different in the two media. the speed is different in the two media. the amplitude is different in the two media.

Light refracts when it passes from air to water because Assessment Questions Light refracts when it passes from air to water because the wavelength is different in the two media. the frequency is different in the two media. the speed is different in the two media. the amplitude is different in the two media.

Which type(s) of lens can form a real image? concave lens only Assessment Questions Which type(s) of lens can form a real image? concave lens only convex lens only both concave and convex lenses neither concave nor convex lenses

Which type(s) of lens can form a real image? concave lens only Assessment Questions Which type(s) of lens can form a real image? concave lens only convex lens only both concave and convex lenses neither concave nor convex lenses