21. What does the term ‘order of magnitude’ refer to?

• a) The precision of a measurement
• b) The power of 10 closest to the quantity
• c) The accuracy of a measurement
• d) The dimensional analysis
• Answer: b) The power of 10 closest to the quantity

22. A physical quantity expressed in terms of mass, length, and time is known as:

• a) Fundamental quantity
• b) Derived quantity
• c) Vector quantity
• d) Scalar quantity
• Answer: b) Derived quantity

23. The least count of a micrometer screw gauge is:

• a) 0.01 mm
• b) 0.02 mm
• c) 0.05 mm
• d) 0.1 mm
• Answer: a) 0.01 mm

24. The SI unit of energy is:

• a) Joule
• b) Calorie
• c) Electronvolt
• d) Erg
• Answer: a) Joule

25. The accuracy of a measurement depends on:

• a) The instrument used
• b) The observer’s skill
• c) The environmental conditions
• d) All of the above
• Answer: d) All of the above

26. The unit of power in the SI system is:

• a) Watt
• b) Joule
• c) Newton
• d) Volt
• Answer: a) Watt

27. Which of the following instruments is used to measure the diameter of a thin wire?

• a) Vernier caliper
• b) Screw gauge
• c) Ruler
• d) Spherometer
• Answer: b) Screw gauge

28. The dimensional formula for work is:

• a) [M L^2 T^-2]
• b) [M L T^-2]
• c) [M L T^-1]
• d) [M T^-2]
• Answer: a) [M L^2 T^-2]

29. What is the SI unit of luminous flux?

• a) Candela
• b) Lumen
• c) Lux
• d) Watt
• Answer: b) Lumen

30. The precision of an instrument refers to:

• a) The smallest measurement it can make
• b) The accuracy of its measurements
• c) The repeatability of its measurements
• d) Its ability to measure accurately
• Answer: c) The repeatability of its measurements