Barometer Practice Questions
19 free Barometer practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which scientist is credited with inventing the first mercury barometer in 1643?
- A Blaise Pascal
- B Evangelista Torricelli
- C Daniel Gabriel Fahrenheit
- D Otto von Guericke
Correct answer: Evangelista Torricelli
Evangelista Torricelli, a student of Galileo, invented the mercury barometer. He demonstrated that the height of a mercury column was supported by the pressure of the surrounding atmosphere.
What is the primary purpose of a barometer in meteorology?
- A To measure relative humidity
- B To measure wind speed and direction
- C To measure atmospheric pressure
- D To measure solar radiation
Correct answer: To measure atmospheric pressure
A barometer is a scientific instrument used specifically to measure air pressure. Changes in atmospheric pressure are key indicators of shifting weather patterns.
Why is mercury preferred over water in a standard liquid barometer?
- A Mercury is less toxic than water.
- B Mercury's high density allows a much shorter tube.
- C Water does not expand or contract with temperature.
- D Mercury is a better conductor of heat.
Correct answer: Mercury's high density allows a much shorter tube.
Because mercury is about 13.6 times denser than water, a mercury barometer only needs a tube about 76 cm tall. A water-based barometer would require a tube over 10 meters high to measure the same pressure.
A sudden and rapid fall in the barometric reading usually indicates which of the following?
- A Clear skies and stable, sunny weather
- B An approaching storm or cyclone
- C Extreme cold weather
- D Decreasing humidity
Correct answer: An approaching storm or cyclone
A rapid drop in air pressure typically signifies a low-pressure system moving into the area. This is often associated with unstable air, clouds, and stormy weather.
Which type of barometer does NOT use any liquid to measure pressure?
- A Fortin barometer
- B Torricellian barometer
- C Aneroid barometer
- D Kew barometer
Correct answer: Aneroid barometer
The word 'aneroid' means 'without liquid.' It uses a small, flexible metal box called an aneroid cell that expands or contracts with changes in air pressure.
What is the standard atmospheric pressure at sea level in millimeters of mercury (mmHg)?
- A 100 mmHg
- B 560 mmHg
- C 760 mmHg
- D 1013 mmHg
Correct answer: 760 mmHg
Standard sea-level pressure is defined as 760 mmHg (or 760 torr). This is the height of the mercury column that the atmosphere can support under standard conditions.
How does barometric pressure change as an observer moves to a higher altitude?
- A It increases linearly.
- B It remains constant.
- C It decreases steadily.
- D It increases exponentially.
Correct answer: It decreases steadily.
As altitude increases, the density of the air and the amount of atmosphere above the observer decrease. Consequently, the weight of the air column (pressure) decreases as one goes higher.
What is the space above the mercury in a simple barometer tube called?
- A Torricellian vacuum
- B Pascal's void
- C Atmospheric dead space
- D Rarefied zone
Correct answer: Torricellian vacuum
The Torricellian vacuum is the empty space at the top of the barometer tube. It contains almost no air and only a negligible amount of mercury vapor.
Which unit of pressure used on many barometers is equivalent to 100 Pascals?
- A Kilopascal
- B Standard atmosphere
- C Pounds per square inch
- D Hectopascal
Correct answer: Hectopascal
One hectopascal (hPa) is equal to 100 Pascals (Pa). A kilopascal is 1,000 Pa, a standard atmosphere is 101,325 Pa, and one pound per square inch is about 6,895 Pa.
What is a 'barograph'?
- A A device that measures the chemical composition of air
- B A barometer that uses water instead of mercury
- C A barometer that records pressure changes over time
- D An instrument for measuring the weight of an object
Correct answer: A barometer that records pressure changes over time
A barograph is a recording barometer. It uses a pen and a rotating drum to create a continuous graph of atmospheric pressure changes over a set period.
In an aneroid barometer, what part of the instrument reacts directly to pressure changes?
- A A glass lens
- B A mercury reservoir
- C A partially evacuated metal capsule
- D A coiled bimetallic strip and spring
Correct answer: A partially evacuated metal capsule
The heart of an aneroid barometer is the aneroid capsule. This thin metal chamber is partially evacuated of air, allowing it to flex inward or outward as external pressure changes.
What happens to the mercury level in a barometer if it is taken inside a pressurized airplane cabin?
- A It will drop significantly.
- B It will stay the same as at sea level.
- C The mercury will boil away because of the low pressure.
- D It will rise relative to the level outside the plane.
Correct answer: It will rise relative to the level outside the plane.
Pressurized cabins maintain a higher pressure than the thin air outside. Therefore, the mercury level inside the cabin would rise to reflect that higher internal pressure.
The 'Fortin Barometer' is known for high accuracy because it allows for:
- A Adjustment of the mercury cistern to a zero point
- B Electronic data logging
- C The simultaneous use of two different measuring liquids
- D Automatic correction for gravity
Correct answer: Adjustment of the mercury cistern to a zero point
The Fortin barometer features an adjustable leather bottom on the cistern. This allows the user to align the mercury surface precisely with an ivory 'zero' point before taking a reading.
If a barometer is submerged in a swimming pool, the reading will increase. Why?
- A Water is much colder and denser than the air at the surface.
- B The instrument is sensitive to humidity.
- C Mercury reacts chemically with water.
- D It measures both atmospheric pressure and water pressure.
Correct answer: It measures both atmospheric pressure and water pressure.
Barometers measure total pressure. Under water, the instrument must support the weight of both the air above the pool and the water above the instrument itself.
Which of the following would NOT affect the reading of a mercury barometer?
- A The local value of gravity (g)
- B The temperature of the mercury
- C The altitude of the location
- D The diameter of the glass tube
Correct answer: The diameter of the glass tube
As long as the tube is wide enough to avoid excessive capillary action, the height of the mercury column depends on pressure and density, not the tube's diameter.
Why must barometric readings be 'corrected' for temperature?
- A Mercury expands and contracts with temperature.
- B Cold air is under higher pressure than warm air.
- C Glass tubes break easily in the cold.
- D Air pressure is not affected by temperature.
Correct answer: Mercury expands and contracts with temperature.
The density of mercury changes with temperature, which changes the height of the column even if air pressure is constant. Scientists use correction tables to normalize readings to a standard temperature.
An altimeter, used in aviation to determine height, is actually a modified version of which instrument?
- A Hygrometer
- B Anemometer
- C Bimetallic thermometer
- D Aneroid barometer
Correct answer: Aneroid barometer
Since air pressure drops predictably with altitude, an aneroid barometer can be calibrated in feet or meters instead of pressure units to serve as an altimeter.
If air pressure is 'rising,' what kind of weather is typically expected?
- A Fair, calm, and clear weather
- B Heavy rain and severe thunderstorms
- C A sharp drop in air temperature
- D An increase in wind speed
Correct answer: Fair, calm, and clear weather
Rising pressure usually indicates a high-pressure system (anticyclone) is moving in. High-pressure systems typically bring stable, dry air and clear skies.
What is the primary advantage of an aneroid barometer over a mercury barometer?
- A It is portable and does not spill.
- B It is much more precise.
- C It does not require calibration.
- D It can measure pressures below one millibar.
Correct answer: It is portable and does not spill.
Aneroid barometers are compact, rugged, and contain no toxic liquid, making them ideal for use in homes, ships, and airplanes where a 3-foot glass tube of mercury would be impractical.