Question

At a given place the barometer reads 72 cm and the weather is fair for two days, this implies that the given place is

• A. at sea level
• B. on some hill
• C. below the sea level
• D. none of the above

Answer 1

The correct option is B

on some hill

Explanation of correct option:

option b)

1. A barometer is a device that is used to measure atmospheric pressure at a place.
2. The rise or fall in the level of mercury shows the variation in the pressure from place to place.
3. At sea level the vertical height of mercury supported in the tube is 76 cm.
4. As we move up to the higher altitudes, due to a decrease in the weight of the air the atmospheric pressure decreases.
5. Due to a decrease in pressure the level of mercury in the barometer at higher altitudes for example; at hills, also decreases.
6. This results in the value of atmospheric pressure less than 76 cm at higher altitudes or hilly areas.

Explanation of incorrect option:

option a)

1. At sea level the atmospheric pressure is 76 cm of mercury in the barometer.

option c)

1. When we move down into a mine it is found that the weight of air increases.
2. This increases the weight of air and hence increases the atmospheric pressure which results in the rise in the level of mercury in the barometer.

Thus, option (b) on some hill is the correct option.