Shorter wavelengths are more dangerous at lower power levels.

Shorter wavelengths are more dangerous at lower power levels.

• A. True
• B. False
• C. Not sure
• D. It depends

Answer: (A)

Shorter wavelengths are more dangerous at lower power levels because photon energy increases as wavelength decreases. Since energy per photon is hc/λ, blue or violet light delivers more energy per photon than red light when the radiant power is the same. That higher photon energy makes it easier to initiate damage-inducing processes—such as photochemical reactions or bond breakage in tissues—even if the overall power is low. In the eye and skin, shorter wavelengths are often absorbed more readily, concentrating energy where it can cause harm, so the threshold for damage is lower. Longer wavelengths tend to rely more on heating to cause injury and generally require higher power or longer exposure to reach the same damage level. Therefore, at lower power, shorter wavelengths pose a greater risk.

Shorter wavelengths are more dangerous at lower power levels because photon energy increases as wavelength decreases. Since energy per photon is hc/λ, blue or violet light delivers more energy per photon than red light when the radiant power is the same. That higher photon energy makes it easier to initiate damage-inducing processes—such as photochemical reactions or bond breakage in tissues—even if the overall power is low. In the eye and skin, shorter wavelengths are often absorbed more readily, concentrating energy where it can cause harm, so the threshold for damage is lower. Longer wavelengths tend to rely more on heating to cause injury and generally require higher power or longer exposure to reach the same damage level. Therefore, at lower power, shorter wavelengths pose a greater risk.