Chem & Phy review Flashcards
What are strong acids? Give examples
Sulfuric acid (H2SO4) Nitric acid (HNO3) Hydrochloric acid (HCl) Hydrobromic acid (HBr) Hydroiodic acid (HI) Chloric acid (HClO3) Perchloric acid (HClO4)
What is the incident ray of light?
The light ray as it approaches the reflective surface
Reflected ray
The light ray once it bounces off/reflects off the surface
What’s the angle of incidence?
This is the angle between “the normal line” and the incident ray.
What’s the angle of reflection?
This is the angle between normal and the reflected ray
In light, what’s the normal line?
This is the line perpendicular to the surface of medium
Where does light travel the fastest?
In a vacuum, or, for the MCAT, air.
Velocity = c = 3x10^8 m/s
Define the index of refraction
Known as “n” = c/v = speed of light in a vacuum / speed of light in the medium
This is a proportion between speed of light in vacuum to the speed of light in that new medium.
Snell’s Law
What’s total internal reflection?
At a point when the incident angle surpasses the critical angle, a light ray doesn’t pass into the other medium, but it reflects back into the first medium.
What’s critical angle?
This is the incident angle at which the refracted angle is 90 degrees. Anything greater than this angle will cause total internal reflection.
Note that refraction DOES occur, but it skirts along the boundary between the two mediums
Converging lens
Type of lens with both sides curving outward. It will bend light from distant objects inward toward focal point - they converge at a point.
Diverging lens
Lens where both sides curve inward, light from objects will bend outward as they pass through lens. The focal point is on the same side of the lens where light rays do come from.
Focal length
Distance from the focal point to the lens/mirror
- Converging lens/mirror - focal length is positive
- Diverging lens/mirror - focal length is negative
How many focal points does a lens have?
Two!
Because light can enter on each side of a lens.
How do we know when a focal length is positive or negative?
Look at the lens/mirror you have!
- Convex lens, concave mirror/converging lens/mirror: focal length is positive
- Concave lens, convex mirror/diverging lens: focal length is negative
How do we know when the image length, for some image cast by a lens, is negative or positive?
- Image length is positive when the image is cast by the lens on the opposite side of the object
- Image length is negative when the image is cast by the lens on the same side as the object
Give the formula relating focal length, image distance, and object distance for both mirrors and lenses
What is the magnification formula?
Magnification (M) = -i/o
- i = image distance
- o = object distance
What does a negative and positive magnification mean, in terms of orientation of an image?
When i is negative, magnification is positive - this means that the image is upright.
(M = -(-i)/o = i/o)
When i is positive, magnification is negative - the image is inverted.
M = -(+i)/o = -i/o
Describe the electromagnetic spectrum
This describes the full range of electromagnetic waves.
Radio waves are at one end - low frequency, long wavelength, low energy
Gamma rays are the other extreme - high frequency, short wavelength, high energy
What is the wavelength of a radio wave?
Wavelength: 109 - 1 m
Frequency: 104 - 1011 Hz
In a vacuum, at what speed do electromagnetic waves travel?
They travel at 3 x 108 m/s, or
the speed of light.
This is represented by the constant, “c.”
How do we relate the speed of a wave to its frequency and wavelength?
Velocity of the wave = f x ƛ
For light:
c = f x ƛ
Describe the visible region of the electromagnetic spectrum
This is the only part of the electromagnetic spectrum that can be perceived by the human eye.
- Violet (ƛ = 400 nm) is at one end of the spectrum
- Red (ƛ = 700 nm) at other end
- Order of colors in spectrum: ROY G BV (Red, Orange, Yellow, Green, Blue, Violet)
The law of reflection
The law of reflection, in words, is that the angle between an incident light ray and normal is the same as the angle between the reflected light ray and normal.
What is reflection, in terms of light?
This is when some incident light wave “rebounds” at the interface of a medium.
In optics, what is the “normal” line?
It is a line drawn perpendicular to the boundary of a medium - the angle of a light ray is measured relative to this.
(Normal is reminiscent of the normal force - perpendicular to a surface)
Describe the difference between real and virtual images
Real image: this is when light actually converges where the image is.
Virtual image: Light doesn’t actually converge where the image is; light appears to be coming from the image.
Describe the two types of spherical mirrors - where are each of their center/radius of curvature?
The two types of spherical mirrors are concave and convex.
The center of curvature can be thought of as the center of the mirror, if it were shaped as a sphere.
Concave - the center/radius of curvature would be located in front of it.
Convex - the center/radius of curvature would be located behind it.
What’s another name for concave mirror?
Converging mirror
What’s another name for convex mirror?
Diverging mirror
How can we relate the focal length of a mirror to its radius of curvature?
f = r/2
(Focal length is half of radius of curvature)
f = focal length (distance between focal point and mirror)
r = radius of curvature (distance between center of curvature and mirror)
How can we know when an image is real or virtual, for a mirror?
When the image length is positive, this is a real image, located in front of the mirror.
When the image length is negative, this is a virtual image, located behind the mirror.
How can we draw a ray diagram for some object, with a concave/converging mirror?
From the top of the object, draw the following:
1) Ray parallel to the principal axis that strikes the mirror, then reflects back through the focal point
2) Ray that passes through the focal point, strikes the mirror, then reflects back parallel to the principal axis
3) Ray that hits the center of the mirror, then reflects from the mirror at an angle equal to the angle at which it struck the mirror (represents law of reflection)
When an object is placed further from the focal length, but not at 2F, for a concave/converging mirror, what kind of image is generated?
Real, inverted, magnified
When an object is placed at the exact focal point in front of a concave/converging mirror, what kind of image is formed?
NONE
When an object is placed closer to the focal point in front of a concave mirror, what kind of image is formed?
Virtual, upright, magnified
What kind of image is formed when an object is placed in front of a convex, diverging mirror?
Virtual, upright, reduced
When light enters a medium with a higher index of refraction from a medium of lower index refraction, does the refracted ray bend toward or away from normal?
As it enters a medium with a higher index of refraction, it bends towards normal
When light enters a medium with a lower index of refraction, does the refracted ray bend toward or away from normal?
It bends away from normal as it enters a medium with lower index of refraction.
In what situations does total internal reflection occur?
To surpass the critical angle, light must bend away from normal. Therefore, light must be traveling to a medium with lower index of refraction.
What is the power of a lens, and what is its equation?
The power of a lens is measured in diopters.
P = 1/f
F= focal length
Power can assume the same sign as f; that is, since f is positive for converging lenses, power is positive.
Myopia
Nearsightedness.
This requires divergent lenses/divergence of light to correct for it
Hyperopia
Farsightedness.
People that have this need converging lenses to correct
For a multiple lens system, what is the total magnification?
M = M1 x M2 x M3…
(Total magnification is equal to the magnification of each lens multipled together)
Dispersion
This refers to when various wavelengths of light separate from each other as they refract through some medium with “n” index of refraction; for example, white light being split into ROY G BV when it travels through a prism.
This occurs because these different wavelengths travel at different speeds
Diffraction
This is when light spreads out as it passes through a narrow opening or goes around some obstacle.
For a slit-lens system, how can we find the location of the minima/dark fringes?
a sin θ = nƛ
a = width of slit
n = integer indicating fringe number (odd numbers = minima)
ƛ = incident wavelength
For a multiple slit lens system, how can we calculate the positions of minima/dark areas?
The equation is
d sin θ = (n+0.5)ƛ
d = distance between slits
What’s the formula to calculate decibels?
dB = 10 * log (I / 10-12)
I = intensity of sound
What image is formed when an object is placed at 2F for a converging lens/mirror?
Real, inverted, same size
What kind of image is formed when an object is placed further than 2F in front of a converging mirror/lens?
Real, inverted, reduced
