Light. 1. c. Earth. Moon. d. Speed of Light 1. d = 240,000 mi. c = v = 2d/t. c = (2)(240,000 mi)/2.58 s. t = 2.58 s. c = 186,000 mi/s. c = ? mi/s. c = 3 x 10 8 m/s. Earth. d. Speed of Light 2. How many round trips can a beam of light make around the earth in 1 second?.
dSpeed of Light 2
How many round trips can a beam of light make around the earth in 1 second?
1, 10, 100, 1,000 ?
d = 8,000 mi
Distance traveled in 1s = 186,000 mi
r = 4,000 mi
1 round trip = 2 π r = 2(3.14)(4,000 mi)
v = 186,000 mi/s
# of trips = 186,000 mi/ 2(3.14)(4,000 mi)
C = 2 π r
# of trips = approximately 8
v = 2 c
Year 2006Faster than the Speed of Light
Spaceship leaves Earth traveling at 2c
Spaceship arrives on Planet X.
Light from takeoff is
half way to Planet X.
Light from takeoff arrives on Planet X.
Space traveler watches his takeoff.
To travel into the future you would have to travel faster than the speed of light.
v = f
For red f is low, is long
For blue f is high, is short
λ is smaller
f is higher
λ is larger
f is lower
The visible region of the spectrum is of course of particular interest to us. Figure 33-2 shows the relative sensitivity of the human eye to light of various wavelengths. The center of the visible region is about 555 nm, which produces the sensation that we call yellow-green
The limits of this visible spectrum are not well defined because the eye-sensitivity curve approaches the zero-sensitivity line asymptotically at both long and short wavelengths. If we take the limits, arbitrarily, as the wavelengths at which eye sensitivity has dropped to 1% of its maximum value, these limits are about 430 and 690 nm; however, the eye can detect electromagnetic waves somewhat beyond these limits if they are intense enough.
Primary Colors of Light
Red + Green = Yellow
Red + Blue = Violet
Red + Green + Blue = White
The following substances are listed in alphabetical order. Arrange them in order of value of index of refraction. Remember, the higher the index of refraction, the slower the speed of light in that substance:
water.Index of Refraction of Various Materials
The image is formed on the retina.
The image is inverted and real.
As the object distance varies, the lens of the eye contracts or expands to change it’s focal length so that the image always forms on the retina.
For a telescope, the focal length of the objective lens is large.
For a microscope, the focal length of the objective lens is small.
The focal length of the objective lens is large.
The object is at infinity.
1/f = 1/do + 1/di
1/f = 1/ + 1/di
1/f = 1/di
di ≈ f
The image formed by the objective lens is at the focal point and is real.
The image formed by the eyepiece is virtual and magnified.
In a microscope, the focal length of the objective lens is small. Why?
Because the object must be very close to the objective lens.
In a telescope, the focal length of the objective lens is large. Why?
Because the object is very far from the objective lens.