Light, Mirrors and Lenses

What are the primary subtractive colors?

magenta, cyan, yellow

What are the primary additive colors?

red, green, blue

What color does a red light and a blue light make?

magenta

(concave mirror) The object is placed beyond the center of curvature

real, inverted, smaller

(concave mirror) the object is placed at the center of curvature

real, inverted, same size

(concave mirror) the object is placed between the center of curvature and the focal point

real, inverted, bigger

(concave mirror) the object is placed at the focal point

no image is formed

(concave mirror) the object is placed between the focal point and the mirror

virtual, upright, bigger

real image

it is formed due to actual intersections of the rays (inverted)

virtual image

it is formed when the rays meet if they are produced backwards (upright)

How is the focal point and the center of curvature related in a spherical mirror?

the focal point is half of the center of curvature

How far away does the image in a flat mirror appear to be from the object that is reflected?

Twice as far away as the object is from the mirror.

What kind of image do flat mirrors make?

virtual, upright, same size

How are the angles of incidence and refraction related?

they are equal

specular reflection

results in parallel rays being reflected and an image being formed

diffuse reflection

causes the rays to come off in random directions, no image is formed

What happens to light intensity as you double your distance from the light source?

Light intensity is inversely proportional to the square of the distance. Doubling your distance decreases your intensity by a factor of four.

Why is it that you can determine the frequency of any form of electromagnetic wave if you know the wavelength?

All electromagnetic waves travel at c = 3*10^8 m/s. So the equation c = f(wavelength) has two known values.

How do speeds of different forces of electromagnetic radiation compare?

They are all the same c = 3*10^8 m/s.

What region of the electromagnetic spectrum do we use when we see things?

visible light

What region of the electromagnetic spectrum is used for television transmissions?

Radio waves

How is a rainbow formed?

Incoming light rays enter water droplets and are dispersed into different colors. Those light rays reflect off the back of the droplet toward a viewer with red light on the bottom and violet light on top. The violet light from droplets higher in the air is not seen - only the red ones are. Violet light from lower droplets are seen with the rays from the red end of the spectrum being unseen.

How does atmospheric refraction affect the sunrise and sunset?

Atmospheric refraction causes us to see the sun before it actually comes over the horizon in the morning and after it has set at night.

How do mirages form?

Mirages form when light that normally would go to the ground is refracted upward by warmer air.

What is the critical angle and how does it relate to total reflection?

The critical angle is the angle (from the normal) at which total internal reflection occurs. If light strikes at an angle less than the critical angle then some light will go through the boundary.

Focal lengths for converging (convex) lens

positive focal lengths

Focal lengths for diverging (concave) lens

negative focal lengths

What sign does a vertical image have and where does it form?

Virtual images have negative signs (q is negative). Virtual images form on the same side of a lens as the object.

What sign does a real image have and where does it form?

Real images have positive signs (q is positive) and form on the opposite side of the lens as the object.

What kind of images can a converging (convex) lens form?

Converging (convex) lenses can form real, inverted images that are smaller, the same size, or bigger than the object. They can also form virtual, upright, larger images when the object is inside the focus.

What kind of image can a diverging (concave) lens form?

always form upright, virtual, smaller images

What do light rays have to do in order to form a real image?

Light rays have to converge on the opposite side of a lens.

When does light refract towards the normal?

when n1 < n2

When does light refract away from normal?

when n1 > n2

How is light speed affected when it passes from one medium to another?

Light either speeds up or slows down when going from one medium to another. When light passes into a medium with a higher index of refraction it slows down. When it passes into a medium with a lower index it speeds up.

When does light NOT refract

Light doesn't refract if one substance is not transparent, if the angle from the normal is 0 degrees, or if both substances have the same index of refraction (n).

What is refraction

Refraction is the bending of light through a medium.