Physics A: Problem Set 15: The nature of light
recommended reading
High Marks: | n/a |
Barron's Let's Review: | 12.1–12.4 |
physics.info: | The nature of light |
Wikipedia: | Light, Speed of light, Visible spectrum |
HyperPhysics: | Speed of light, Visible light |
Khan Academy: | Introduction to light waves |
YouTube: | Roy G. Biv |
Mr. Machado: | 15 Wave Phenomena - From Sound to Light |
homework
- Using the Reference Tables for Physical Setting/PHYSICS, determine the color of the 9 different light waves below with the following characteristics:
- A frequency of…
- 4.30 × 1014 Hz
- 5.63 × 1014 Hz
- 6.34 × 1014 Hz
- A wavelength of…
- 4.21 × 10−7 m
- 4.73 × 10−7 m
- 5.87 × 10−7 m
- A period of…
- 1.78 × 10−15 s
- 1.96 × 10−15 s
- 2.03 × 10−15 s
- A frequency of…
- Autonomous cars use lidar to determine the distance to objects around them using pulses of laser light. The word lidar is an acronym of light detection and ranging and was intended to mimic the words radar (radio detection and ranging) and sonar (sound navigation and ranging). A detector near the laser measures the time between when a pulse was sent out and when a reflection was received back. Some systems also compare the wavelength of the reflected laser light to the wavelength transmitted. Optical data for one particular lidar system are given in the table below.
Automotive lidar system characteristic value wavelength 905 nm pulse duration 3 ns pulse power 8 W beam divergence 0.12° - What type of electromagnetic radiation does this laser emit?
- What is the energy in one pulse of this laser?
- If the time of flight for one pulse to hit an object and return is 40 ns, how far away is the object from the car?
- If the reflected laser light has a wavelength of 904.99994 nm, what additional information does this tell you about the distance between the object and the car?