Question

Range of visible spectrum of solar radiations primarily absorbed by plants for photosynthesis is

• A. 340-450 nm
• B. 400-700 nm
• C. 450-950 nm
• D. 500-600 nm

Answer 1

The correct option is B 400-700 nm

Visible light is the observable electromagnetic spectrum which is visible to human eyes. The visible spectrum ranges from the infrared region to the UV region. The human eye can detect the light spectrum ranging from 400 nanometres (violet) to about 700 nanometres (red). Other electromagnetic radiations are either too small or too large to be captured by the human eye and are out of biological limitations.

Visible wavelengths of light are captured by chlorophyll-bearing plants, which then make their own food through the process of photosynthesis.

The long wavelengths of the light spectrum— red, yellow, and orange— can penetrate to approximately 15, 30, and 50 metres respectively, while the short wavelengths of the light spectrum— violet, blue and green— can penetrate further, to the lower limits of the euphotic zone. Blue penetrates the deepest, which is why deep, clear ocean water and some tropical water appear to be blue most of the time.