A boy with a mouth 5cm wide stands 2m away from a plane mirror. Where is his image and how wide is the image of his mouth?
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The image will form 2m behind the mirror and the width of the image of boy’s mouth will be 5cm.
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Explain with a suitable diagram, how a concave mirror converges a parallel beam of light rays. Mark clearly the pole, focus and centre of curvature of concave mirror in this diagram.
List four precautions which a student should observe while determining the focal length of a given convex lens by obtaining image of a distant object on a screen.
Redraw the following diagram on your answer sheet and show the path of the reflected ray. Also mark the angle of incidence $(\angle\text{i})$ and the angle of reflection $(\angle\text{r})$ on the diagram.
The refractive index of water with respect to vacuum is $\frac{4}{3}$ and refractive index of vacuum with respect to glass is $\frac{2}{3}$ If the speed the speed of light in glass is $2 \times 10^8 ms^{-1}$, find the speed of light in (i) vacuum, (ii) water.