Chapter 27 - Light
How far is a light second?
300,000 km
Infrared waves are responsible for sunburns.
False
Materials that allow light to pass through them in straight lines are called opaque materials.
False
Which one of these electromagnetic waves has the shortest wavelength?
X-rays
Solar eclipses are seen less commonly than lunar eclipses because _____.
Earth's shadow on the moon is larger than the moon's shadow on Earth
A thin beam of light is called an X-ray.
False
Electromagnetic heat waves are called ultraviolet waves.
False
Glass transmits ultraviolet and visible light waves but not infrared waves.
False
A total shadow is called an umbra.
True
According to Einstein, light consists of massless bundles of electromagnetic energy called photons.
True
Energy emitted by vibrating electric charges is carried by electromagnetic waves.
True
Light sometimes acts as a wave and sometimes as a particle.
True
Polarization occurs when waves vibrate in a single direction.
True
The distance light travels in one year is called a light year.
True
What is the ultimate source of electromagnetic waves?
Vibrating charged particles
Explain how light is transmitted through glass. Why is ultraviolet radiation not transmitted through glass?
Visible light is transmitted through glass by molecules that do not easily absorb light photons. A light photon is absorbed for a very short time by a glass molecule, but then is reemitted in the same direction it was originally traveling and with the same frequency it originally had
The main difference between a radio wave and a sound wave is its _____.
basic nature
Glass is transparent to visible light, but not to _____.
both a and b (ultraviolet and infrared)
Light reflected from the lake surface is polarized _____.
horizontally
Compared to the wavelength of ultraviolet rays, the wavelength of infrared rays is _____.
longer
Light does not pass through what kind of materials?
opaque
Light that reflects at glancing angles from nonmetallic surfaces, such as glass, water, or roads is _____.
polarized parallel to the surface
The shadow produced by an object held close to a piece of paper in sunlight will be _____.
sharp
Electromagnetic waves with higher frequencies have wavelengths that are _____.
shorter
Compared to its speed in air, the speed of light in water is _____.
slower
Which of the following is NOT an electromagnetic wave?
sound
Which of the following are fundamentally different from the others?
sound waves
The shiny surfaces of metals have most to do with _____.
the free electrons in metal atoms
Compared to the velocity of the radio waves, the velocity of visible light waves is _____.
the same
The primary purpose of polarized sunglasses is _____.
to block glare from reflections
Clouds _____.
transmit UV light
Electromagnetic waves are _____.
transverse waves
Light waves are _____.
transverse waves
The source of all electromagnetic waves is _____.
vibrating charges
The main difference between a radio wave and a light wave is its _____.
wavelength
If two polarizing filters are held with their polarization axes at right angles to each other, the amount of light transmitted compared to when their axes are parallel is _____.
zero