Introduction To Physics And Measurement - SS1 Physics Past Questions and Answers - page 2

Fundamental quantities are the basic physical quantities that are not defined in terms of other quantities. They are those basic physical quantities which do not depend on any other physical quantities for their measurement.

• Luminous Intensity: The fundamental quantity for measuring the intensity of light emitted by a source. Its unit is the candela (cd).
• Amount of Substance: The fundamental quantity for measuring the number of entities (such as atoms or molecules) in a substance. Its unit is the mole (mol).

The correct answer is C, Infrared thermometer, because it measures temperature without physically touching the object.

• Caliper: Requires direct contact to measure dimensions.
• Stopwatch: Measures time, which doesn't relate to contact or non-contact.
• Infrared thermometer: Measures temperature by detecting infrared radiation emitted by an object.
• Weighing scale: Requires direct contact to measure mass.