Physics 2 Ch. 26 Online HW
What is the frequency of an electromagnetic wave that has a wavelength of 300,000 km?
1 Hz
If the Sun were to disappear at this moment, we wouldn't know about it for how long?
8 minutes
While Earth is experiencing a total sphere eclipse, an observer on the side of the Moon facing Earth would see:
A dark area moving across the face of Earth
When an astronaut on the Moon experiences a solar eclipse, observers on Earth see:
A lunar eclipse
Which best shields you from sunburn when at the beach? (A sheet of glass between you and the sun, a cloudy day, frequent turning of your body)
A sheet of glass between you and the sun
The main difference between the retina of a human eye and that of a dog's eye is the:
Absence of cones in a dog's retina
Materials generally become warmer when light is:
Absorbed by them
The source of all electromagnetic waves is:
Accelerating electric charges
Which of these travel with the greatest speed in a vacuum? (Game Rays, x-rays, radio waves, light waves)
All of them have the same speed
A total shadow is called:
An umbra, and a partial shadow a penumbra
Glass is transparent to wave frequencies that:
Are below its natural frequencies
When visible light is incident upon clear glass, atoms in the glass:
Are forced into vibration
Information-carrying nerves are connected to the retina at the:
Blind spot
If a light signal and a radio signal were emitted simultaneously from Alpha Centauri, the first to reach Earth would be:
Both of them at the same time
The sensation of color is seen when light falls on the eye's:
Cones
An annular eclipse of the Sun occurs when the Moon doesn't quite cover the Sun in the zone of totality. This means that the Moon is:
Farther than usual from the Earth
A main difference between a radio wave and a light wave is:
Frequency and wavelength
If an electron vibrates up and down 1000 times each second, it generates an electromagnetic wave having a:
Frequency of 1000 Hz
Infrared waves are often called heat waves because they:
Induce resonance in molecules and increase internal energy in a substance
Earth's atmosphere is opaque to waves that are concentrated in the:
Infrared part of the spectrum
Most of the waves in an electromagnetic spectrum are:
Invisible
Colors are barely seen or not at all in nighttime because moonlight:
Is too dim to activate the retina's cones
Compared to average speed in air, the average speed of a beam of light in glass is:
Less
If an electric charge is shaken up and down frequently enough:
Light can be emitted
Compared to ultraviolet waves, the wavelength of infrared waves is:
Longer
If the color spectrum ranges from red to violet, then it ranges from:
Low frequencies to high frequencies and low wavelengths to high wavelengths
Compared to ultraviolet waves, the frequency of infrared waves is:
Lower
The moon would be at its fullest just before the time of a:
Lunar eclipse
A changing electric field includes a changing:
Magnetic field
A main difference between a radio wave and a sound wave is:
Medium or no medium
A lunar eclipse occurs when the:
Moon passes into Earth's shadow
What is the wavelength of an electromagnetic wave that has a frequency of 3 kilohertz?
More than 1 km
What is the wavelength of a 1-hertz electromagnetic wave?
More than 1 m
The cones in the retina of the eye are:
Most densely packed at the center of vision
Electromagnetic waves consist of:
Oscillating electric and magnetic fields
The fact that you can see stars in the nighttime sky is evidence that:
Our atmosphere is transparent to visible light and light can travel in a vacuum
A partial solar eclipse occurs for people in the Sun's:
Penumbra
Which of these electromagnetic waves has the longest wavelength? (Radio waves, infrared waves, light waves, x-Rays, ultraviolet waves)
Radio waves
Which color of light gets through red glass? (Red,cyan)
Red
When ultraviolet light is incident upon glass, atoms in the glass:
Resonate
In the periphery of our vision, we are:
Sensitive to movement, but cannot see color
A new Moon appears in the sky just before the time of a:
Solar eclipse
Which of the following can't travel in a vacuum? (Light wave, radio wave, sound wave)
Sound wave
Which of these fundamentally differ from the others? (Radio waves, x-rays, gamma rays, sound waves, light waves)
Sound waves
A pair of sunglasses and a pair of clear reading glasses are left in the sunlight. The hotter glasses will be the:
Sunglasses
A solar eclipse occurs when:
The Moon's shadow is cast on Earth
The round spots of light on the ground beneath a tree on a sunny day are images of:
The Sun
The size of the pupil in your eye depends on:
The brightness of light in the room and your mood
Compared to radio waves, the velocity of visible light waves in a vacuum is:
The same
Consider light energy that is momentarily absorbed in glass and then re-emitted. Compared to the absorbed light, the frequency of the re-emitted light is:
The same
The speed of light in the void between molecules in glass is:
The same as its speed in a vacuum
Metals are shiny because:
Their electrons vibrate to the oscillations of any incident light
Red-hot and blue-hot stars appear whit to the eye because:
They are too dim to fire the cones
Sunburns are produced by:
Ultraviolet light
The natural frequency of the atoms in glass is in the:
Ultraviolet part of the spectrum
A total solar eclipse occurs for people in the Sun's:
Umbra
Glass is transparent to:
Visible light
Which of these electromagnetic waves have the shortest wavelength? (Ultraviolet waves, light waves, infrared waves, radio waves, x-Rays)
X-rays
In 1887, Albert A. Michelson sent a beam of light from a revolving mirror to a stationary mirror 15 km away. Find the time interval between light leaving and returning to the revolving mirror and find a time for a pulse of laser light to reach the Moon and to bounce back to Earth:
t = 1.0 x 10^-4 s t = 2.6 s
The nearest star beyond the Sun is Alpha Centauri, 4.2 x 10^16 m away. If we were to receive a radio message from this star today, find the time when it would have been sent. Find the frequency of this radiation. Find the time required for a pulse of radar waves to each an airplane 4.8 km away and return:
t = 4.4 years ago f = 10 GHz t = 3.2 x 10^-5 s