Advertisements
Advertisements
Question
Observe the given diagram and answer the questions:

- Name the process shown in the figure.
- Name the colour that deviates the most.
- Name the colour that deviates the least.
- Name any one phenomenon in nature which is based on the above process.
- Define ‘spectrum’.
Advertisements
Solution
- The process shown in the figure is the dispersion of light.
- The colour that deviates the most is violet.
- The colour that deviates the least is red.
- One phenomenon in nature based on the above process is the formation of a rainbow.
- A spectrum is a band of colours, as seen in a rainbow, produced by the separation of the components of light by their different degrees of refraction according to wavelength.
APPEARS IN
RELATED QUESTIONS
A narrow beam PQ of white light is passing through a glass prism ABC as shown in the diagram.

Trace it on your answer sheet and show the path of the emergent beam as observed on the screen DE.
(i) Write the name and cause of the phenomenon observed.
(ii) Where else in nature is this phenomenon observed?
(iii) Based on this observation, state the conclusion which can be drawn about the constituents of white light.
After tracing the path of a ray of light through a glass prism a student marked the angle of incidence (∠i), angle of refraction (∠r) angle of emergence (∠e) and the angle of deviation (∠D) as shown in the diagram. The correctly marked angles are :

(A) ∠i and ∠r
(B) ∠i and ∠e
(C) ∠i, ∠e and ∠D
(D) ∠i, ∠r and ∠e
A student is observing a diagram showing the path of a ray of light passing through a glass prism. He would find that for all angles of incidence the ray of light bends:
In the following diagram the correctly marked angles are :

(a) ∠A and ∠e
(b) ∠i, ∠A and ∠D
(c) ∠A ∠r and ∠e
(b) ∠A ∠r and ∠D
State the cause of dispersion of white light
Name the process which is involved in the formation of a rainbow.
Out of the following, the colour of light having the maximum wavelength is:
(a) violet
(b) indigo
(c) green
(d) orange
Out of air and glass, which is optically rarer? Give reason.
What do you understand by the term spectrum? Name the various colours present in the spectrum of sunlight.
In the following diagram, the correctly marked angles are
(A) All
(B) Only ∠i and ∠A
(C) ∠i, ∠r and ∠A
(D) ∠i, ∠A and ∠D
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
Make the correct choice for each of the following:
Which one of the following Fig correctly shows the path of the ray through the glass block?
A wave has wavelength 50Å of name the wave.
The phenomenon of splitting of light into its component colours is ___________ .
When white light enters a glass prism from the air, the angle of deviation is least for ____________.
State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B, shown in the following figure.

What is Newton’s disc?
When sunlight passes through water droplets in the atmosphere it gets dispersed into its constituent colours forming a rainbow. A similar phenomenon is observed when white light passes through a prism.
Instead of sunlight, a green-coloured ray is passed through a glass prism. What will be the colour of the emergent ray?
Make a rainbow
Try to make your own rainbow. You can try this project in the morning or in the evening. Stand with your back towards the Sun. Take a hosepipe or a water pipe used in the garden. Make a fine spray in front of you. You can see different colours of rainbow in the spray.
