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A glass capillary tube is of the shape of a truncated cone with an apex angle `alpha` so that its two ends have cross sections of different radii. When dipped in water vertically, water rises in it to a high h, where the radius of its cross section is b. If the surface tension of water is S, its density if `rho`, and its contact angle with glass is `theta`, the value of h will be (g is the acceleration due to gravity) A. `(2S)/(brhog)cos(theta-alpha)`B. `(2S)/(brhog)cos(theta+alpha)`C. `(2S)/(brhog)cos(theta-(alpha)/(2))`D. `(2S)/(brhog)cos(theta+(alpha)/(2))` |
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Answer» Correct Answer - D `(b)/(R)=cos(theta+(alpha)/(2))` Using pressure equation along the path MNTK `p_(0)-(2S)/(R)+hrhog=p_(0)` |
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