Units and Measurements – General Science

 Units and Measurements – General Science

Units & Measurements is an important topic in General Science and Physics. Questions from this topic are frequently asked in SSC, Railway, UPSC, State PSC, Police and other competitive examinations.

         

📏 What is Measurement?

Measurement is the process of comparing an unknown physical quantity with a standard quantity of the same kind.

A unit is a fixed standard used for measuring a physical quantity.

SI System of Units

The International System of Units (SI) is the internationally accepted system of measurement.

Physical Quantity

SI Unit

Symbol

Length

metre

m

Mass

kilogram

 kg

Time

second

s

Electric Current

ampere

A

Temperature

kelvin

K

Amount of Substance

mole

mol

Luminous Intensity

candela

cd

These are the 7 fundamental SI units.

🔹 Important Derived SI Units

Physical Quantity

SI Unit

Symbol

Area

square metre

m²

Volume

cubic metre

m³

Speed

metre/second

m/s

Acceleration

metre/second²

m/s²

Force

newton

N

Work/Energy

joule

J

Power

watt

W

Pressure

pascal

Pa

Frequency

hertz

Hz

Electric Charge

coulomb

C

Voltage

volt

V

Resistance

ohm

Ω

🔢 Common Unit Conversions

1 kilometre = 1000 metres

1 metre = 100 centimetres

1 centimetre = 10 millimetres

1 kilogram = 1000 grams

1 gram = 1000 milligrams

1 hour = 3600 seconds

1 minute = 60 seconds

1 litre = 1000 millilitres

⭐ Important Measuring Instruments

Length – Metre scale

Small length/diameter – Vernier calipers

Very small thickness/diameter – Screw gauge

Temperature – Thermometer

Atmospheric pressure – Barometer

Electric current – Ammeter

Potential difference – Voltmeter

Mass – Beam balance

Time – Stopwatch

Relative density – Hydrometer

📝 15 Important MCQs

1. What is the SI unit of length?

A) Centimetre

B) Metre

C) Kilometre

D) Millimetre

Answer: B) Metre

2. What is the SI unit of mass?

A) Gram

B) Tonne

C) Kilogram

D) Milligram

Answer: C) Kilogram

3. What is the SI unit of time?

A) Minute

B) Hour

C) Second

D) Day

Answer: C) Second

4. What is the SI unit of force?

A) Joule

B) Newton

C) Watt

D) Pascal

Answer: B) Newton

5. Which instrument measures atmospheric pressure?

A) Thermometer

B) Barometer

C) Ammeter

D) Hydrometer

Answer: B) Barometer

6. What is the SI unit of power?

A) Joule

B) Newton

C) Watt

D) Volt

Answer: C) Watt

7. Which instrument is used to measure electric current?

A) Voltmeter

B) Ammeter

C) Barometer

D) Galvanometer

Answer: B) Ammeter

8. What is the SI unit of temperature?

A) Celsius

B) Fahrenheit

C) Kelvin

D) Joule

Answer: C) Kelvin

9. What is the SI unit of frequency?

A) Hertz

B) Watt

C) Pascal

D) Newton

Answer: A) Hertz

10. What is the SI unit of energy?

A) Watt

B) Joule

C) Newton

D) Pascal

Answer: B) Joule

11. Which instrument is used to measure very small thicknesses?

A) Metre scale

B) Screw gauge

C) Barometer

D) Stopwatch

Answer: B) Screw gauge

12. 1 kilometre is equal to:

A) 10 m

B) 100 m

C) 1,000 m

D) 10,000 m

Answer: C) 1,000 m

13. What is the SI unit of pressure?

A) Newton

B) Pascal

C) Joule

D) Watt

Answer: B) Pascal

14. Which SI unit is used for electric current?

A) Volt

B) Ohm

C) Ampere

D) Coulomb

Answer: C) Ampere

15. Which instrument is used to measure temperature?

A) Thermometer

B) Barometer

C) Ammeter

D) Hydrometer

Answer: A) Thermometer

🎯 Exam Quick Revision

7 Fundamental SI Units:

Metre – Length

Kilogram – Mass

Second – Time

Ampere – Electric Current

Kelvin – Temperature

Mole – Amount of Substance

Candela – Luminous Intensity

Remember:

Force → Newton

Energy → Joule

Power → Watt

Pressure → Pascal

Frequency → Hertz

Voltage → Volt

Resistance → Ohm

📌 Practice Daily

For more General Science Notes, MCQs, Current Affairs and Government Job Updates, visit:

govtjobsalerts.in