What is a light ray?
A light ray is an idealized way by which we model light. It is drawn as a straight line and allows us to draw diagrams modeling the motion and behavior of light. While light can be more closely and accurately characterized as a wave in which it has peaks and troughs, if you draw a line tangential to those peaks and troughs, the resultant line is a ray that points in the direction the energy is flowing.
A light ray is an idealized way by which we model light. It is drawn as a straight line and allows us to draw diagrams modeling the motion and behavior of light. While light can be more closely and accurately characterized as a wave in which it has peaks and troughs, if you draw a line tangential to those peaks and troughs, the resultant line is a ray that points in the direction the energy is flowing.
What is specular reflection?
Specular reflection is when light reflects off of smooth surfaces which include mirrors and calm, unmoving water. The other type of reflection is called diffuse reflection. Diffuse reflection is basically just the opposite of specular reflection since it is the reflection of light off of rough surfaces which include paper and clothing.
Specular reflection is when light reflects off of smooth surfaces which include mirrors and calm, unmoving water. The other type of reflection is called diffuse reflection. Diffuse reflection is basically just the opposite of specular reflection since it is the reflection of light off of rough surfaces which include paper and clothing.
What is a paraxial ray?
A paraxial ray is a ray that is close to and nearly parallel with the optical axis in an optical system.
A paraxial ray is a ray that is close to and nearly parallel with the optical axis in an optical system.
Converging vs. Diverging Mirrors
Converging Mirrors
As light passes through a converging mirror, the light converges to one point to make an image. Converging mirrors can produce both real and virtual images. If the object is located outside the focal point, the image is real and inverted. However, if the object is placed inside the focal point the image becomes virtual and upright.
Converging Mirrors
As light passes through a converging mirror, the light converges to one point to make an image. Converging mirrors can produce both real and virtual images. If the object is located outside the focal point, the image is real and inverted. However, if the object is placed inside the focal point the image becomes virtual and upright.
Diverging Mirrors
When light passes through a diverging mirror, the light rays diverge and only virtual images are created.
When light passes through a diverging mirror, the light rays diverge and only virtual images are created.
Real vs. Virtual Images
Real images are created when light actually converges. This happens when an object is either placed outside the focal length of a converging lens or converging mirror. On the other hand, virtual images just appear to be where light converges. This happens when an object is placed in front of a diverging lens or if the object is placed inside the focal length of a converging lens.
Real images are created when light actually converges. This happens when an object is either placed outside the focal length of a converging lens or converging mirror. On the other hand, virtual images just appear to be where light converges. This happens when an object is placed in front of a diverging lens or if the object is placed inside the focal length of a converging lens.
Problems:
A point source of light is from a large opaque barrier that has an L-shaped aperture, dimensions shown. Light is viewed on a screen that is away from the source. Sketch an image of what you would see on the screen, and show any relevant dimensions.
A student has built a 20 cm long pinhole camera for science fair projects. She wants to photograph a 550 ft tall building and have the image be 2 in high. How far should she stand from the building?
A light bulb is suspended form the ceiling and hangs in front of a mirror, as shown in the diagram below. If a student walks parallel to the mirror, how far away can they be and still see the image of the light bulb in the mirror?
If the student is walking 1 meter away parallel to the mirror then the student can be 4m away and still see the image of the light bulb in the mirror. This is because the angle of incidence is equal to the angle of reflection.
If the student is walking 1 meter away parallel to the mirror then the student can be 4m away and still see the image of the light bulb in the mirror. This is because the angle of incidence is equal to the angle of reflection.
A fish looks out the side of an aquarium at a can nearby. The can is from the end of the aquarium. To the fish, does it appear to be closer, farther, or the same distance?
The can will appear to be farther away due to refraction and reflection of light going into the eyes of the fish. The light will bend due to the difference in the indexes of refraction of air and water. This will create an image of the can appear further away than the actual object.
The can will appear to be farther away due to refraction and reflection of light going into the eyes of the fish. The light will bend due to the difference in the indexes of refraction of air and water. This will create an image of the can appear further away than the actual object.
A -2 cm high object is placed 60 cm from a 4 cm diameter lens. A sharply focused image is seen on a screen on the other side of the lens, and is 2 cm high.
a.) What is the focal length of the lens?
a.) What is the focal length of the lens?
b.) Suppose the screen is moved so that it is twice as far away. What will be seen?
c.) Now an aperture is placed in front of the lens. An aperture is an opaque piece that covers the entire lens, except for a small pinhole in the center. What will you see on the screen with this aperture in place?
The image will stay the same.
The image will stay the same.
Two converging lenses with focal lengths of 40 cm and 20 cm are placed 10 cm apart. A 2 cm tall object is placed 15cm from the 40cm lens.
a.) Describe all the features of the final image (upright/inverted, real/virtual, smaller/larger, etc.).
Inverted, real, larger
b.) Find the exact location and height of the final image.
a.) Describe all the features of the final image (upright/inverted, real/virtual, smaller/larger, etc.).
Inverted, real, larger
b.) Find the exact location and height of the final image.
A converging lens with focal length of and a diverging lens with a focal length of are placed apart. A tall object is placed from the converging lens.
a.) Describe all the features of the final image (upright/inverted, real/virtual, smaller/larger, etc.).
Inverted, virtual, same size
b.) Find the exact location and height of the final image.
a.) Describe all the features of the final image (upright/inverted, real/virtual, smaller/larger, etc.).
Inverted, virtual, same size
b.) Find the exact location and height of the final image.