Unit 2: Optics

1. Bring tomorrow for optics unit: A ruler, protractor and sci calculator Unit 2: Optics

2. What is light? • List some characteristics of light. • Energy that is transmitted without needing a medium. (Radiation) • Light travels at 299 792 km/s (3X10 8 m/s) in straight lines • Visible Spectrum is ROYGBV • Light is an electromagnetic wave. Sound Needs a medium

4. As wave energy increases , amplitude increases. • Frequency: # waves that pass per second. • As frequency increases, its wavelength decreases.

5. Relationships between Frequency and Wavelength • Frequency and wavelength have an inverse relationship, which means that as one increases, the other decreases. • As frequency increases, wavelength decreases • As frequency decreases, wavelength increases

6. There is a mathematical relationship between wavelength and frequency as well as wave speed. ν = ƒ λ ν = speed of wave (m/s) ƒ = frequency of wave (Hz or 1/s or s-1) λ = wavelength (m)

7. Examples: What is the speed of the wave if the frequency is 5 cycles per second and the wavelength is 10 cm? ν = ? ƒ = 5/s λ = 10 cm = 0.1 m ν = ƒ λ ν = (5/s)(0.1m) ν = 0.5 m/s Therefore the speed is 0.5 m/s.

8. What is the frequency of the speed of the wave is 100 cm/s and the wavelength is 25 cm? ƒ = ? ν = 100 cm/sλ = 25 cm ν = ƒ λ ƒ = ν / λ ƒ = (100 cm/s)/(25 cm) ƒ = 4/s Therefore the frequency is 4 cycles per second.

9. What is the frequency if the same wave is 100 cm/s and the wavelength is 5 cm? ƒ = ? ν = 100 cm/sλ = 5 cm ν = ƒ λ ƒ = ν / λ ƒ = (100 cm/s)/(5 cm) ƒ = 20/s Therefore the frequency is 20 cycles per second.

10. Light has the same velocity, but different wavelength and frequency than other waves in the electromagnetic spectrum.

13. Homework • Complete wavelength worksheet(posted on my class site-using book • HMWK: Read 464-478