Saved Bookmarks
| 1. |
Why is mercury preferred as a barometric substance over water? |
|
Answer» The pressure exerted by column of a liquid equal to that of atmosphere depends inversely on density of the liquid. Because p = hρg or h ∝ 1/ρ (for a constant p). Since mercury is a most denser liquid available, therefore by using it, the barometric arrangement will be of very convenient size. Suppose the atmospheric pressure is 1.01 x 105 Pa. Then the height of water barometer is, hw = p/ρwg = {1.01 x 105}/{103 x 9.8} = 10.3 m The height of mercury barometer is, hw = p/ρHgg {1.01 x 105}/{(13.6 x 103 x 9.8)} = 0.76 m Thus, the tube required for water barometer should be long, which is very inconvenient, whereas the tube used in mercury barometer is small, which is convenient to use. |
|