Phys 115 1st Edition Lecture 17Outline of Last Lecture I. Magnetic force II. CurrentIII. SolenoidOutline of Current Lecture IV. Guest presentation: Prof. Sönke JohnsonV. Virtual images and objectsVI. Compound microscopeCurrent Lecture- An object placed closer to a converging lens than the lens’ focal distance (i.e. s<f ) creates a virtual image. - The rays leaving the lens appear to diverge from the image.- Converging and Diverging Lenseso A converging lens bends rays toward the optic axis: f > 0o A diverging lens bends rays away from the optic axis: f < 0o The focal length of a lens depends only on the material it is made of and on the curvature of the surfaces.o The focal length is an intrinsic property of the lens; it does not depend on the object or image distance. - Ray tracing: converging lens, f > 0o Image location can be found by tracing at least two rays from the object.o Three rays are easy to trace:o Rays parallel to the optic axis are refracted through the far focal point.o Rays through the near focal point are refracted parallel to the optic axis.o Rays passing through the center of the lens do not bend.- Ray tracing: diverging lens, f< 0o The image location can be found by tracing at least two rays from the object.o Three rays are easy to trace:o Rays parallel to the optic axis are refracted through the near focal point.o Rays through the far focal point are refracted parallel to the optic axis.o Rays passing through the center of the lens do not bend.- Thin Lens Equation (diverging lens)o If f < 0 and s > 0 → s’ < 0: virtual image 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.o If f < 0 and s < 0 (object to right of lens, virtual object) → s’ can be > 0: real image (see next Monday’s lecture and the visual defect correction in studio #19)- Compound optical systems: the microscopeo A microscope uses two (or more) lenses to form a highly magnified image.o The image from the first lens is the object for the second lens.o Each lens produces magnification, so overall magnification is large.- Questiono You have a microscope that has an eyepiece lens. You wish to photograph the image you see when you look through the microscope. Can you do so by replacing the eyepiece lens with a camera? Give a brief explanation. o No, the final image is virtual and is not located at the
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