Light-year: Unit of Astronomical Distance
A light-year is defined as the distance that light travels in a vacuum during one Julian year (365.25 days).
This unit is commonly used in astronomy and other scientific fields to express the immense distances between astronomical objects such as stars, galaxies, and other celestial bodies.
Despite the name containing "year," which relates to time, a light-year specifically measures length or separation, not duration. It quantifies how far light can travel in that time frame.
Therefore, a light-year is a unit of distance.
- Option 1: Intensity of light - Incorrect. Intensity relates to brightness.
- Option 2: Distance - Correct. This is the definition of a light-year.
- Option 3: Mass - Incorrect. Mass is the amount of matter in an object.
- Option 4: Time - Incorrect. While based on a year, it measures distance traveled *in* that time.
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Important Questions from Physical Quantities
Which instrument is used to measure the intensity of light produced by an unknown source in terms of a standard source?
With what do you divide thrust in a liquid to obtain the value of pressure?
Which of the following is a vector quantity?
A. Time
B. Temperature
C. Distance
D. Velocity
Which of the following is a scalar quantity?
Pressure is measured in terms of
A. Mass & Density
B. Work done
C. Force and Area
D. Force and Distance
