- When constructing the enclosure to detect infrared light in Investigation 22B on page 1277, why is it helpful to cover the inside of the box with black paper?
- Many sound waves can diffract around buildings—which means that a sound made on one side of the building can be heard on the other side.
Light in the visible part of the spectrum, however, cannot diffract around a building—you can’t see what is on the other side of a building.
What is the main difference between them? Does this suggest a part of the electromagnetic spectrum that would be able to diffract around a building?
- When using a triangular glass prism to disperse white light, is it more effective to use a diffuse light source or a narrow beam of light?
- Why do night goggles detect infrared radiation? Why not gamma or ultraviolet radiation?
- Why shouldn’t you look directly at the Sun when using a hand-held visual spectroscope outdoors during a field investigation?
- Describe the photoelectric effect and how it relates to the dual nature of light.
- Polarized glasses block some of the light and reduce glare. Why is it still dangerous to look at the Sun when wearing polarized glasses?
- How is the vibrational frequency of an electromagnetic wave related to its energy?
- Explain what is meant by the number of “megapixels” in a digital camera.
- For the signal of an AM radio station at 1,050 kHz, what does the frequency 1,050 kHz represent?
Is it the frequency of the musical sounds broadcast by the station?
- One student proposed a scientific explanation that light is a particle, based on the photoelectric effect.
A second student tested the first student’s hypothesis by conducting the double slit experiment, which showed that light interferes as a wave. The second student therefore proposed the scientific explanation that light is a wave.
In your evaluation of the two scientific explanations and the evidence, who is right?
- In the double slit experiment for light, how will the spacing of the interference bands (or fringes) vary with the wavelength of the light?
- Sometimes a picture taken with a CCD-based camera shows a long streak trailing from a very bright source, such as a lamp, bright star, or the Sun.
What property of the CCD do you think causes this?
- How much faster do radio waves travel in a vacuum than infrared light?
- How many times faster is light than sound?
- Light takes approximately 8.3 min to travel from the Sun to the Earth. About how far is the Sun from Earth in kilometers?
- Astronomers often state the distances to other stars in terms of light-years. Using scientific notation, calculate the number of kilometers in one light-year. State your answer with two significant figures, using c = 3.0×108 m/s for the speed of light in a vacuum.
- You are directing a science-fiction movie in which Earthlings use light to communicate with the inhabitants of another planetary system. An Earth scientist sends a greeting and receives an answer a few seconds later. Is this possible given what you know about the speed of light? (The nearest star system to our own is roughly 4×1016 m away in the far-southern constellation of Centaurus.)
- The Voyager 1 spacecraft is currently more than 19 billion km from the Earth.
How long will it take a signal sent by the spacecraft to reach the Earth?
- Sort the following kinds of electromagnetic radiation in order of increasing wavelength: yellow light, microwaves, x-rays, ultraviolet light, and violet light.
- Sort the following kinds of electromagnetic radiation in order of increasing frequency: red light, radio waves, gamma rays, infrared light, and green light.
- An electromagnetic wave with the same frequency as the A string on a violin (440 Hz) would lie in what part of the electromagnetic spectrum? How about one with the same wavelength (78.4 cm)? Why are these different?
- Calculate the frequency of electromagnetic radiation that has a wavelength of 5 μm. What kind of electromagnetic radiation is it?
- The Very Large Array radio telescope often observes at a wavelength of 3.6 cm. What is the frequency of these radio waves in gigahertz (GHz)?