# phys2401 formulas

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1. Law of Reflection
• θr = θi
• angle of reflection = angle of incidence
• r = 2f
• (radius) = 2 * (focal length)
3. Mirror/Thin Lens Equation
• 1/do + 1/di = 1/f
• 1 / (distance of object) + 1 / (distance of image) = 1 / (focal length)
4. Lateral Magnification
• m = hi/ho = -di/do
• (magnification) = (height of image) / (height of object) = -(distance of image) / (distance of object)
• note: - is sign convention
5. Index of Refraction
• n = c/v
• (index of refraction) = (speed of light in vacuum) / (speed of light in given material)
6. Snell's Law
• n1sinθ1 = n2sinθ2
• (index of refraction1) * (sine of angle1) = (index of refraction2) * (sine of angle2)

• note: if n2 > n1, then θ2 < θ1.
• ie: if light goes to a medium with higher n (and speed is less), ray is bent toward the normal and vice versa.
7. Critical Angle
• sinθc = n2/n1
• (sine of critical angle) = (index of refraction2) / (index of refraction1)
8. Power of Lens
• P = 1/f
• (power) = 1 / (focal point)
• note: unit is diopter, m-1, (1/m)
9. Angular Magnification/Magnifying Power
• M = θ'/θ = (h/f)/(h/N)
• (angular magnification) = θwith lens / θunaided = [(height of object) / (focal length)] / [(height of object) / (near point of eye)]
• note: N for normal eye is 25
10. Wavelength in Another Medium
• λn = λ/n
• (wavelength in new medium) = (wavelength in air) / (index of refraction of new medium)
11. Interference Equations
• Constructive: dsinθ = mλ
• Destructive: dsinθ = (m+1/2)λ
• (distance between slits) * (sine of angles made with horizontal) = (order + n) * (wavelength)
• note: m = 0, 1, 2, ...
12. Diffraction Equation
• Dsinθ = mλ
• (slit width) * (sine of angle of rays) = (order) (wavelength)
• note: m = +/-1, +/-2, +/-3, ...
13. Rayleigh Criterion
• λ = 1.22λ/D
• (resolvable angle) = 1.22 * (wavelength) / (diameter of lens)
14. Resolving Power (microscope)
• RP = s = fθ = 1.22λf/D
• (resolving power) = (actual distance barely resolvable) = (focal point) * (subtended angle) = 1.22 * (wavelength) * (focal length) / (diameter of lens)
15. Diffraction Grating equation
• dsinθ = mλ
• (distance between slits) * (sine of angles made with horizontal) = (order) * (wavelength)
• note: m = 0, 1, 2, ...
16. Bragg Equation
• 2dsinϕ = mλ
• (distance between atoms) * (sine of measured angle) = (order) * (wavelength)
• note: m = 0, 1, 2, ...
17. Polarization Equation
• I = I0cos2θ
• (intensity of polarized light) = (incoming intensity) * (cosine of angle between polarizer and incoming light)2
18. Brewster's Law
• tanθp = n2/n1
• (tangent of polarizing angle) = (index of refraction2) / (index of refraction1)
 Author: PowLow ID: 35611 Card Set: phys2401 formulas Updated: 2010-09-19 04:21:01 Tags: physics ii phys formulas ttu texas tech Folders: Description: (Important) formulas for Physics 2401 Exam 1 (Ch.32-35) Show Answers: