Advertisements
Advertisements
Question
The frequency range of visible light is from 3.75 × 1014 Hz to 7.5 × 1014 Hz. Calculate its wavelength range. Take speed of light = 3 × 108 m/s.
Advertisements
Solution
Frequency f = 3.75 × 1014 Hz
Velocity of light (C) = 3 × 108 m/s
λ = `C/f`
= `(3 xx 10^8)/(3.75 xx 10^14)`
= `(3000 xx 10^5)/(375 xx 10^12)`
λ = `(8 xx 10^5)/(10^12)`
= `8 × 10^(5 - 12)`
= 8 × 10-7 m
= 8 × 10-7 × 1010 Å
= `8 × 10^(-7+10)`
= 8 × 103 Å
Also, f = 7.5 × 1014 Hz
λ = `C/f`
= `(3 xx 10^8)/(7.5 xx 10^14)` m
= `(3 xx 10^8)/(75 xx 10^13)` m
= `(300)/(75) xx (10^6)/(10^13)`
= `4 × 10^(6 - 13)`m
= 4 × 10-7
= `4 xx 10^(-7 + 10)`
= 4 × 103
= 4000 Å
∴ Wavelength range of visible light is 4000 Å to 8000 Å
APPEARS IN
RELATED QUESTIONS
Draw a ray diagram to explain the term angle of deviation.
Draw a ray diagram to show the dispersion of white light.
(i) A ray of white light breaks up into its components while passing through a glass prism. Draw a ray diagram to show the path of rays.
(ii) Mark the least deviated colour in your diagram
(iii) Why do different coloured rays deviate differently in a prism?
In the figure given alongside, a narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a spectrum YX on the screen.
State the colour seen (i) at X, and (ii) at Y.
In the figure given alongside, a narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a spectrum YX on the screen.
Why do different colours of white light bend through different angles with respect to the incident beam of light?
How does the speed of light determine the optical density of a medium?
What conclusion do you draw about the nature of white light in part (b)?
In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray:
(A) is parallel to the incident ray
(B) perpendicular to the incident ray
(C) is parallel to the refracted ray
(D) bends at an angle to the direction of incident ray
State two properties of ultra-violet radiations which differ from visible light.
Assertion: We can see the rainbow in the sky when the rain starts falling after a spell of bright sunlight.
Reason: The rainbow is formed due to the dispersion of light.
