Physics 012 1st Edition Lecture 26 Outline of Last Lecture I. Diverging Lensa. Equation for magnification same as for mirrors.i. m = hi/ho = -di/dob. Lens equation same as mirror equation.i. 1/f = 1/do + 1/dic. Real images are on opposite side of lens as object, virtual images are on the same side of lens as object.d. Object placed between F (focal point) and 2F (twice focal length from center) creates a real image of increased size.e. Object placed further than 2F form center of lens creates a real image of reducedsize.f. Object placed within focal length creates a virtual image larger than object.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Converging Lensa. Equation for magnification same as for mirrors.i. m = hi/ho = -di/dob. Lens equation same as mirror equation.i. 1/f = 1/do + 1/dic. Focal length is always negative (like with a convex mirror).d. Image will always be virtual.III. Lenses in Combinationa. First lens is treated like object for second lens.b. Only final image can be seen (not image formed after first lens).c. Total magnification can be found by multiplying all individual magnifications.i. mtotal = (m1)(m2)…(mn)Outline of Current Lecture IV. If λ of light is large compared to size of opening that light passes through, we must consider diffraction and interference effects.a. Diffractioni. When light passes through a thin slit it will spread out with curved wave fronts.b. Constructive Interferencei. When light waves of equal amplitude and wavelength are completely in-phase, the amplitude of the resulting wave will have an amplitude twice that the individual light waves.c. Destructive Interferencei. When light waves of equal amplitude and wavelength are completely out-of-phase, the resulting light wave will have an amplitude of zero (completely dark).d. Laser Double-Slit Experimenti. Experiment: Coherent monochromatic light of wavelength λ is incident upon a screen with two narrow slits. λ is much greater than the width of the slits. A screen is placed a distance L from the screen with slits. ii. Where wave fronts meet, there is constructive interference. Where a wave front of one light beam is directly between two wave fronts of the other light beam, there is destructive interference.iii. When projected onto a screen, a series of bright and dark spaces are observed. The bright space at the center is considered mc = 0, countingoutwards with subsequent bright spots (mc = 1, mc = 2, etc). The dark spaces to either side of mc = 0 are considered md = 0, counting outwards with subsequent dark spots (md = 1, md = 2, etc).1. Intensity decreases as m increases.iv. The difference in the distance travelled by the light beam coming from one slit to point P and the distance travelled by the light beam coming from the other slit to point P is called the path length difference and is denoted δ.1. If δ is some multiple of λ (λ, 2λ, 3λ, etc.), there is constructive interference at point P.2. If δ is some half multiple of λ (λ/2, 3λ/2, 5λ/2, etc.), there is destructive interference at point
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