FNI 1F Physics 1 Waves and Light

FNI 1F Physics2 Cycles, Periods and Frequencies Many things occur in cycles: Seasons: Spring, Summer, Fall, Winter (repeat) The moon cycles from full moon to full moon each month. Period is the amount of time it takes for the cycle to repeat. It has units of time like minutes, seconds, hours, days, weeks, years etc. Frequency is the inverse of the period. It is the number of times something repeats in a given time period. Units are per second, /s, s -1, Hertz, Hz, per minute

FNI 1F Physics3 Waves are an important way to get information Most information comes to us in the form of waves: Sound waves, Hearing Light waves, Sight Waves are also important in finding out about the nanoscale. Spectroscopy

FNI 1F Physics4 Waves repeat over a given cycle Waves have this repeating property. The distance (length) between two repeating points on a wave is called the wavelength. These are both low points. The waveform repeats starting at this point.

FNI 1F Physics5 How can waves differ? Low Frequency Long wavelength High Frequency Short wavelength

FNI 1F Physics6 How can waves differ? Large Amplitude Small Amplitude

FNI 1F Physics7 How can waves differ? Phase In Phase Out of Phase

FNI 1F Physics8 Interference of Waves

FNI 1F Physics9 Formulas for Waves c = λf Speed of propagation, c (m/s) is equal to wavelength, λ (m) times frequency, f (/s, Hz, s -1 ) T = 1/f f = 1/T Period, T is equal to one over frequency, f Frequency, f is equal to one over period, T (s)

FNI 1F Physics10 Working with equations Rearrange the letters/symbols first to solve for the variable. Do not plug in the numbers right away until you solve for the variable. Make sure the units come out OK.

FNI 1F Physics11 Example What is the frequency of a photon of wavelength 532 nm?

FNI 1F Physics12 Trigonometry Sine, cosine, tangent Sine = opposite/hypotenuse Cosine = adjacent/hypotenuse Tangent = opposite/adjacent SOH-CAH-TOA Besides being related to triangles sine is the most fundamental type of waveform. Opposite Adjacent Hypotenuse

FNI 1F Physics13 Trigonometry

FNI 1F Physics14 Waves Many physical phenomena are described as waves. Speed of propagation of waves: c = λf y = A sin(2π f t) 2 π radians = 360º Period, seconds, T=1/f Frequency, Hz, 1/s or s -1

FNI 1F Physics15 Light and Optics Electromagnetic radiation  What we see as light is part of the electromagnetic spectrum.  Photon: a unit of electromagnetic energy (light). Photons have no electric charge, they have zero “rest mass” but they do have momentum and energy. 

FNI 1F Physics16 Same side Opposite sides Slinky Lab Sending two pulses

FNI 1F Physics17 A B C D E