- An electromagnetic wave in a vacuum has a wavelength of 0.07 m. What is its frequency? (1 point)
f = 3.0 • 108 m/s
f = 4.3 • 109 Hz
f = 3.0 • 109 Hz
f = 4.3 • 108 m/s
Answer.
1) The speed of the electromagnetic waves is the speed of light, c.
2) The relation between speed, frequency and wavelength is speed = wavelength times frequency.
Solve for the frequency, frequency, f = speed / wavelength
f = c / 0.07 m = 310^8m/s / 0.07m = 4.3 10^9 Hertz
2. Which of the following occurs as light travels farther from its source? (1 point)
Far from the source, photons come together in a small area.
The intensity of light increases as photons move away from the source.
The source gives off less light as photons move away from it.
Far from the source, photons spread over a larger area.
Answer:
Far from the source, photons spread over a larger area.
3. Infrared rays have a shorter wavelength than (1 point)
ultraviolet rays.
X-rays.
radar waves.
gamma rays.
Answer: radar waves.
Note that radars use radio waves and the order of the wavelength are:
radio (longest) > infrared > u-v ray > x-ray > gamma ray (shortest)
4. In order of increasing light-transmitting capabilities of materials, which is the correct sequence? (1 point)
transparentopaquetranslucent
opaquetransparenttranslucent
opaquetranslucenttransparent
translucenttransparentopaque
opaque < translucent < transparent.
Thi is, opaque do not permit the pass of light, translucent permit the pass of light in some grade and transparent permit the maximum pass of light.
5. Which of the following occurs as a light wave bends when it passes from one medium into another? (1 point)
constructive interference
refraction
destructive interference
reflection
Refraction.
Refraction is the change in direction of the wave (light in this case) due to the change of medium..
