Candela is a S.I. unit of -

Appeared in: UPPSC 2023

Explanation

The International System of Units (SI) defines seven base units for fundamental physical quantities.
Candela (symbol: cd) is the designated SI base unit for measuring luminous intensity.
Luminous intensity quantifies the wavelength-weighted power emitted by a light source in a specific direction per unit solid angle.
This is a direct factual recall question from basic physics.

Option B: This is not a standard fundamental physical quantity defined within the SI system. While related to electromagnetism, it does not have a specific base unit.
Option C: The SI base unit for electric current is the Ampere (A), not the Candela (cd).
Option D: Circular motion is a type of movement, not a fundamental physical quantity with a base SI unit. Its characteristics, like angular velocity, are measured in derived units (e.g., radians per second).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain SI Base Units as background academic context rather than a clinical decision trigger.
Understanding fundamental units is a prerequisite for many technical calculations in healthcare, including dosage calculations, interpreting lab results, and operating medical equipment.
In clinical settings, light intensity is a critical parameter. For instance, in phototherapy for neonatal jaundice, the effectiveness is directly related to the intensity (irradiance) of the light source, measured in units like µW/cm²/nm. While not directly candela, it's a related concept of light measurement.
What if the question asked for the unit of electric charge? The answer would be the Coulomb (C), which is a derived unit (Ampere-second), not a base unit.

How to Approach the Question

Identify the key terms in the question: 'Candela' and 'S.I. unit'.
Recognize this as a factual recall question requiring knowledge of fundamental physics units.
Recall the definition of 'Candela'. It is one of the seven base SI units.
Evaluate each option to find the physical quantity that corresponds to the Candela.
Eliminate incorrect options: 'Electric current' is measured in Amperes, 'circular motion' is a type of movement, and 'electromagnetic current' is not a standard term for a base quantity.
Conclude that 'Luminous intensity' is the correct quantity measured in Candelas.

Concept Tested & Keywords

Q4Do3cv8cIs7Jwk5Hu89OC

E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart B (pp 233-449 of 464) pp. 57-59, 58-60

Practise the full UPPSC 2023

Attempt every question from this paper in a timed mock, then review the full solution for each one.