Which law states that the energy carried by radiation is proportional to its frequency?

• A. Planck's Law
• B. Newton's Law
• C. Ohm's Law
• D. Boyle's Law

Answer: (A)

Energy in radiation is carried by quanta whose energy scales with frequency. Planck introduced the idea that light comes in discrete packets, each with energy E equal to Planck's constant h times the frequency f, so E = h f. This means higher-frequency radiation (like blue light) delivers more energy per quantum than lower-frequency radiation (like red light). That linear relationship between energy and frequency is the essence of Planck's law and underpins the quantum description of light. The other laws mentioned describe different phenomena (motion or circuit behavior or gas pressure–volume relationships) and do not link the energy of radiation to its frequency.