Which statement best describes inverse square law?

Which statement best describes inverse square law?

• A. Quantities fall off linearly with distance
• B. Quantities fall off with the square of distance
• C. Quantities increase with distance squared
• D. Quantities are independent of distance

Answer: (B)

The inverse square law describes how a quantity that radiates from a point source decreases because the same amount spreads over a larger surface area as distance increases. The amount per unit area falls off with the square of the distance, so the intensity scales as I ∝ 1/r^2. This means that if you double the distance, the effect becomes one quarter as strong; three times the distance gives one-ninth, and so on. This happens because a sphere’s surface area grows with r^2, spreading the same total quantity over more area. The law applies to things like light intensity, gravitational pull, and electric field strength at a distance, provided the source can be approximated as a point source. So the correct description is that quantities fall off with the square of distance. Linear decrease, increasing with distance, or being independent of distance do not fit.

The inverse square law describes how a quantity that radiates from a point source decreases because the same amount spreads over a larger surface area as distance increases. The amount per unit area falls off with the square of the distance, so the intensity scales as I ∝ 1/r^2. This means that if you double the distance, the effect becomes one quarter as strong; three times the distance gives one-ninth, and so on. This happens because a sphere’s surface area grows with r^2, spreading the same total quantity over more area. The law applies to things like light intensity, gravitational pull, and electric field strength at a distance, provided the source can be approximated as a point source. So the correct description is that quantities fall off with the square of distance. Linear decrease, increasing with distance, or being independent of distance do not fit.