5p2 Waves and Particle Nature of Light Flashcards
Describe an experiment to measure how the frequency of the first harmonic is affected by the length, tension and mass per unit length of string
Set one end of a string to a vibration generator and pass the other end over a pullet and secure it to a mass hanger - measure length of string - turn on signal generator to set the string to oscillate - increase frequency until the first harmonic is reached which is nodes on either end and an antinode in the middle and record this frequency - record this frequency for different lengths and plot frequency against length - repeat for effect of mass per unit length by changing the string and tension by hanging mass hanged and plot graphs of frequency against these variables
What are the results from this experiment ( measure how the frequency of the first harmonic is affected by the length, tension and mass per unit length of string
)
Longer the string - lower frequency, heavier string - lower frequency (waves travel slower), higher tension - higher frequency (waves travel faster down tight string)
What is diffraction
Diffraction is the spreading out of waves as they pass through or around a gap
Describe an experiment to determine the wavelength of light from a laser
Place laser on a stand and the diffraction grating in front - use set square t ensure beam passes through grating at a normal (perpendicular) - set the distance between grating and screen to 1m - turn on laser and identify zero order maximum on screen - measure the distance from the zero order to the two first order maxima and calculate a mean - measure this distance for other orders - repeat with different diffraction grating - use diffraction grating equation to calculate wavelength
How did the model of light develop over time
First believed to be a particle explaining reflection and refraction, then believed to be a wave due to diffraction, then discovered it had wave-particle duality due to photoelectricity discovery
