What is the SI unit of pressure?
- A.Volt
- B.Ampere
- C.Pascal
- D.Ohm
Show answer
Correct answer: C. Pascal
Explanation
The correct answer is C, Pascal. Pressure is force acting per unit area, so its SI unit is the newton per square metre, which is given the special name pascal (Pa) after the French scientist Blaise Pascal, who stated the law of transmission of pressure in liquids used in hydraulic brakes and lifts. One pascal is a very small pressure, so larger units are common: 1 bar = 10⁵ Pa, 1 atmosphere = 101,325 Pa = 760 mm of mercury, and weather reports use the hectopascal (1 hPa = 100 Pa), while blood pressure is still read in mm Hg. Option A is wrong because the volt is the SI unit of electric potential difference (1 V = 1 J/C). Option B is wrong because the ampere is the SI base unit of electric current. Option D is wrong because the ohm is the SI unit of electrical resistance (1 Ω = 1 V/A). Exam tip: pressure = force ÷ area, N/m² = pascal; and the electrical trio: volt for voltage, ampere for current, ohm for resistance.