Question

light of wavelength 5000 A.U. in air. Find the number of waves of light in a path length of 5 cm​

Answer 1

Wavelength of light in air = 5000A° (A° is the symbol for Angstrom Unit)

Now 1 A° = 10^-8 cm

Wave length of light in air = 5000 A° = (5000 A°) × (10^-8 cm/A°) = 5 × 10^-5 cm

Number of waves of light of wavelength 5000 A° in 50 cm of air = (50 cm) ÷ ( 5 × 10^^-5 cm) = 10^6 waves.

A million waves of wavelength 5000A° can be accommodated in 50 cm of air.

Let us check = (number of waves) × wavelength of the wave = 10^6 × 5×10^-5 cm = 10 × 5 cm = 50 cm.