A plane mirror forms the familiar image you see when you look into a bathroom mirror. In this lesson, you will trace how reflected light creates that image and learn why its location, size, and orientation have the properties they do.
Light from a point on an object travels toward a plane mirror and reflects according to the law of reflection: the angle of incidence equals the angle of reflection. The reflected rays then travel toward an observer's eye.
All flashcards
How can you locate the image of a point using reflected rays?
Draw the rays reflected from the mirror toward the observer, then extend them backward behind the mirror. Their apparent intersection marks the image of the point.
What is a virtual image?
A virtual image is located where light rays appear to originate, even though the rays do not physically pass through that location. It can be seen but cannot be projected onto a screen.
What are the size and orientation of a plane-mirror image?
It is the same size as its object and upright, meaning it has the same up-and-down orientation.
How are object distance and image distance related in a plane mirror?
Their magnitudes are equal, so the image is as far behind the mirror as the object is in front. With signed distances, do=−di.
How does a real image differ from a virtual image?
Light rays physically pass through a real image, so it can be projected onto a screen. A virtual image is only an apparent source of rays and cannot be projected onto a screen.
Quiz questions
What does the law of reflection state about the angles of an incoming and reflected ray?Answer: The angle of incidence equals the angle of reflection.
Why can a virtual image formed by a plane mirror not be projected onto a screen?Answer: Light rays do not physically pass through the image location.
An object is 0.8 m in front of a plane mirror. How far behind the mirror is its image?Answer: 0.8 m
With two mirrors, how can one mirror produce an image of an image formed by the other?Answer: The first mirror's image acts as an object for the second mirror.
Which direction is reversed by reflection, rather than the object's up-and-down orientation?Answer: The front-to-back direction.
Based on University Physics Volume 3 by Samuel J. Ling, Jeff Sanny, William Moebs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.