Light and Optics Flashcards
Electromagnetic spectrum
The spectrum that graphs all the electromagnetic radiations of various wavelengths and frequencies.
Describe the visible light spectrum
ROY G BIV
RED = 700nm ( long wavelength, low frequency, low energy)
VIOLET = 400nm ( short wavelength, high energy, and high frequency).
What is the color of an object?
The color of an object is the wavelength that is reflected off of it. All other wavelengths are absorbed.
Blackbody
Object that absorbs all wavelengths and therefore appears completely black.
What type of waves are electromagnetic waves?
Transverse waves. Electric and magnetic fields are perpendicular to each other and to the propagation of the wave ( and thus the energy of the wave).
How to calculate the speed of light?
C= ( frequency)*(wavelength) , where C is 3x10^8. This frequency and wavelength are perpendicular to each other.
What causes refraction and reflection
Waves that travel in a homogenous mixture travel in a straight path called rectilinear propagation. However when it changes media it causes reflection and refraction.
Reflection
The bouncing of the incident wave ( incoming wave) off the media. This creates an incident angle and reflected angle that are equal to each other. Measured with respect to the normal ( perpendicular line to the normal).
Real v. virtual images
Real images formed with light converges at the image. Virtual images are formed with light appears to becoming from the image.
Describe plane mirrors
Only produces virtual images because the light rays reflect off the front of the mirror but the image appears behind the mirror.
Spherical mirrors
They REFLECT light.
Center of curvature is the center point if the mirror created a complete sphere. The radius of curvature is the distance from the sphere surface to the center of curvature.
For concave and convex mirrors where are the center of curvatures and radius of curvatures located?
For concave( converging) mirrors they’re located in front. For convex ( diverging) mirrors they’re located behind.
What is the focal length (f)?
The distance between the focal point ( F) and the mirror.
To find the focal length we take 1/2 of the radius of curvature.
How to determine if an image is real or virtual?
We calculate the image distance. If it’s positive the image is in front of the mirror and real. If it’s negative the image is behind the mirror and is virtual.
What does the magnification tells us?
Whether an object is upright or inverted, or if it’s enlarged or reduced. Dimensionless value so no units.
Calculated by dividing image of distance ( multiplied by negative value). Or the height of the image divided by the height of the object.
What does it mean when the magnification is positive, negative? Larger or smaller than one?
If m is positive the image is upright if m is negative the image is inverted. If the absolute value of m is greater than one the image is enlarged compared to the object. If absolute value is less than one the image is reduced compared to the object.
What does it mean when O is positive, negative?
What about i?
Positive- object is in front of mirror.
Negative- object is in behind mirror.
Positive- image is in front of mirror. Negative- image is behind mirror.
What happens we r is positive, negative? What about f?
If r or f is positive than the mirror is concave ( converging).
If r or f is negative than the mirror is convex ( diverging).
How do we relate speed of light in a vacuum ( C), speed of light in medium ( V), and index of refraction (n)?
n= c/v
Snell’s law
Relates the index of refraction and angles of both incident rays and incident rays.
Total internal refraction
When light moves from a medium with higher index of refraction to medium with lower index of refraction you can get all the rays refracted back into the medium. The angle at which this occurs is the critical angle ( refracted angle) and is 90 degrees.
How does lenses differ from spherical mirrors?
Lenses refract light while mirrors reflect it.
- For lens there are 2 focal points and 2 focal lengths. Each on the other side of lens, the focal lengths are the same distance on either side.
Describe the shape of diverging lens v. converging lens
- Diverging lens are narrow in the center but wide at the edges.
- Converging lens are wide at the center and narrow at the edges.
Lensmaker’s equation
Used for real lenses in which the thickness cannot be negligible.
