Recent content by MrMoose

  1. M

    Find magnification of a fish in a fish bowl

    Homework Statement A goldfish in a spherical fish bowl of radius R is at the level of the center of the bowl and at distance R/2 from the glass. What magnification of the fish is produced by the water of the bowl for a viewer looking along a line that includes the fish and the center, from...
  2. M

    Find index of refraction of a sphere given the beam path

    Homework Statement A beam of parallel light rays from a laser is incident on a solid transparent sphere of index of refraction n1 (see figure). (a) If a point image is produced at the back of the sphere, what is the index of refraction of the sphere? (b)What index of refraction, if any, will...
  3. M

    Find angle required for total internal reflection of a beam of light

    Nice, Thanks ehild! I think I got it now. Taking up from just before the incorrect equation: 90 - arcsin(sin(θa)/n1) > arcsin(n2/n1) sin[90 - arcsin(sin(θa)/n1)] > n2/n1 using the following property for sine: sin(x-y) = sinx*cosy - cosx*siny sin(90)*cos[arcsin(sinθa/n1)] -...
  4. M

    Find angle required for total internal reflection of a beam of light

    Homework Statement An optical fiber consists of a glass core (index of refraction n1) surrounded by a coating (index of refration n2<n1). Suppose a beam of light enters the fiber from air at an angle θ with the fiber axis as shown in attached. (a) Show that the greatest possible value of θ...
  5. M

    Light refraction problem in water & air

    Oh wow, that was a silly mistake. So... Tan(55°) = 50cm/X1 X1 = 0.35m And X = X1 + X2 = 1.07m, which is the correct answer. Thanks so much for your help.
  6. M

    Find angle of polarizing sheet given original & transmitted intensity

    Great, Thanks Haruspex. So when I consider the following: θ1 = (arccos(-2*sqrt(0.1)) + 90) / 2 I get θ1 = 109.62° , which is also 19.62° off the normal. That wraps it up!
  7. M

    Light refraction problem in water & air

    Hi mfb, please elaborate, I still don't see the error. Tangent of the angle is equal to the length of the opposite side over the length of the adjacent side.
  8. M

    Light refraction problem in water & air

    Homework Statement In the figure attached, a 2.00m long vertical pole extends from the bottom of a swimming pool to a point 50.0cm above the water. Sunlight is incident at 55.0° above the horizon. What is the length of the shadow of the pole on the level bottom of the pool? Homework...
  9. M

    Find angle of polarizing sheet given original & transmitted intensity

    Thank you! I read that question over so many times and missed that part every time. I think I got it now: I1 = Io*cos^2(θ1) I2 = I1*cos^2(θ2) Where θ2 = 90 - θ1 We also know that I2 = 0.10 * Io, therefore: I2 = 0.1 * Io = Io * cos^2(θ1) * cos^2(90-θ1) Io cancels out and you...
  10. M

    Find angle of polarizing sheet given original & transmitted intensity

    Homework Statement A beam of polarized light is sent through a system of two polarizing sheets. Relative to the polarization direction of that incident light, the polarizing directions of the sheets are at angles θ for the first sheet and 90° for the second sheet. If 0.10 of the incident...
  11. M

    Determine Radiation pressure at angle given Perpendicular Pressure

    Thanks Nascent Oxygen, I'm having a lot of trouble visualizing this problem and radiation pressure in general. I know that Pr for a beam that is totally reflected along the original path is just dependent on the Intensity and speed of light: Pr = 2*I / c It's twice what it would be for a beam...
  12. M

    Determine Radiation pressure at angle given Perpendicular Pressure

    Homework Statement A laser beam of intensity I reflects from a flat, totally reflecting surface of area A whose normal makes an angle θ with the direction of the beam. Write an expression for the radiation pressure Pr[θ] exerted on the surface, in terms of the pressure Pr[p] that would be...
  13. M

    Determine Radiation pressure given the fraction of total absorption

    Holy smokes. Thanks. Pra + Prr = (frac)*I/c + 2*(1-frac)*I/c = I*frac/c + 2*I/c - 2*frac*I/c = (2 - frac)*I / c
  14. M

    Determine Radiation pressure given the fraction of total absorption

    Homework Statement Radiation of intensity I is normally incident on an object that absorbs a fraction frac of it and reflects the rest back along the original path. What is the radiation pressure on the object? Homework Equations Radiation pressure Pr (force/unit area) Pra = I/c...
  15. M

    Find frequency given wavelength and distance travelled

    Ok, I just got the right answer. The wave speed, v, is the speed of light, c: v = c With this knowledge, you can move on to steps 4 and 5 and get the right answer. My next question is... why? I though EM waves only travel at the speed of light through a vacuum. Should I have assumed that...
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