Because it doesn't have an atmosphere or its atmosphere is very thin
Mercury is a liquid over a wide range of temperature ( -39 to 357 degrees ) so it can be used in a variety of temperature ranges. Secondly it does not stick to the glass tubing of the thermometer so when the temperature falls ( i.e. after the reading is taken) all the mercury falls back into the reservoir. This ensures the accuracy of the mercury thermometer.
Mercury's melting point is close to the room temperature, so it is a good indicator of temperature around room temperature.
One of the reasons is that mercury is a liquid at room temperature so we can use Mercury in a thermometer in a room to see the temperature of something.
to see what is the temperature The Mercury expands or contracts depending on the temperature so its height against the scale on the thermometer tells you the temperature.
to see what is the temperature The mercury expands or contracts depending on the temperature so its height against the scale on the thermometer tells you the temperature.
Mercury is a liquid at room temperature; this made it a useful substance in thermometers. As the mercury heated up, it expanded; this indicated the temperature of the surroundings. Similarly, the colder it got, the more the mercury 'shrunk' so it indicated the low temperature.
the liquid has to be at room temperature.
Like most other substances, mercury takes up the temperature of its surroundings, so its average temperature must be room temperature, unless you put it into somewhere hot or somewhere cold.
Mercury. So close to the Sun, it bakes in its long daytime, but having no appreciable atmospere to spread the heat, loses it to space during the night. Earth's Moon, and indeed, all airless worlds, also display dramatic temperature shifts, but Mercury's got the hottest seat in the house, so to speak.
Mercury thermometres aren't used much, because the mercury inside is poisones, But the reason that mercury used to be used is because Mercury expands rapidly, conserning the temperature e.g. if it gets hotter, the Mercury expands, so there is more of it. So, when you're measuring the tempurature, you're actually measuring how much mercury is there, therefore telling you what the temperature.
Mercury is toxic, so you have to be careful not to spill itMercury changes volume/density with temperature (which mercury thermometers rely on) so you have to correct for this when reading them.
It has a reaction to temperature, so it'd be perfect for measuring it!