# lecture20 - Physics 102 Lecture 20 Interference Unaided Eye...

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Unformatted text preview: Physics 102: Lecture 20 Interference Unaided Eye Bring object as close as possible (to near point d near ) How big the object looks with unaided eye. ** If θ is small and expressed in radians. o near h d θ ≈ tan( ) o near h d θ = 47 θ object d near h Angular Size Preflight 19.6, 19.7 • Angular size tells you how large the image is on your retina, and how big it appears to be. • How small of font can you read? Highwire Caramel Apples Rabbits Kindergarten Hello Arboretum Hal owe n Amazing θ θ θ θ 46 Both are same size, but nearer one looks bigger. θ / = h i d i = h o d o Magnifying glass produces virtual image behind object, allowing you to bring object to a closer d o : and larger θ ′ Compare to unaided eye: : near h d θ = Ratio of the two angles is the angular magnification M: o o near o near o h d d M h d d θ θ ′ = = = Magnifying Glass 48 / θ object virtual image h i h o d i d o magnifying glass M = d near /d = d near /f +1 1 1 1 o near d f d = + For max. magnification, put image at d near : so set d i = -d near : Angular Magnification 50 / θ object virtual image h i h o d o magnifying glass (d near = near point distance from eye.) d i Smaller f means larger magnification See text, Example 24.6 o o near o near o h d d M h d d θ θ ′ = = = For the lens: 1 d o + 1 d i = 1 f ⇒ 1 d o = 1 f- 1 d i Phys 102 recent lectures • Lecture 14 – EM waves • Lecture 15 – Polarization • Lecture 20 & 21 – Interference & diffraction • Lecture 16 – Reflection • Lecture 17 – Spherical mirrors & refraction • Lecture 18 – Refraction & lenses (today!) • Lecture 19 – Lenses & your eye Light as a wave Light as a ray Superposition t +1-1 t +1-1 t +2-2 + Constructive Interference In Phase 5 Superposition t +1-1 t +1-1 t +2-2 + Destructive Interference 7 Out of Phase 180 degrees Superposition ACT...
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lecture20 - Physics 102 Lecture 20 Interference Unaided Eye...

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