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# Selina solutions Selina ICSE Concise Physics for Class 10 chapter 6 Spectrum

## Chapter 6 - Spectrum

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Name three factors on which the deviation produces by a prism depends and state how does it depend on the factors stated by you.

How does the deviation produced by a triangular prism depend on the colours (or wavelengths) of light incident on it?

Which colour of white light is deviated by a glass prism the most and which the least?

Define the term dispersion of light.

Explain the cause of dispersion of white light through a prism.

Explain briefly, with the help of a neat labelled diagram, how white light gets dispersed by a prism.

The diagram shown below in Fig. 6.11 shows the path taken by a narrow beam of yellow monochromatic light passing through an equiangular glass prism. Now the yellow light is replaced by a narrow beam of white light incident at the same angle. Draw another diagram to show the passage of white light through the prism and label it to show the effect of prism on the white light.

How does the speed of light in glass change on increasing the wavelength of light?

Which colour of white light travels (a) fastest (b) slowest, in glass?

Fig 6.12 shows a thin beam of white light from a source S striking on one face of a prism.

Complete the diagram to show effect of prism on the beam and to show what is seen on the screen.

Fig 6.12 shows a thin beam of white light from a source S striking on one face of a prism.

A slit is placed in between the prism and the screen to pass only the light of green colour. What will you then observe on the screen?

Fig 6.12 shows a thin beam of white light from a source S striking on one face of a prism.

What conclusion do you draw from the observation in part (b) above?

If a monochromatic beam of light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base?

If white light is used in same way as in part (a) above, what change is expected in the emergent beam?

what conclusion do you draw about the nature of white light in part (b)?

What do you understand by the term spectrum?

A ray of white light is passed through a glass prism and spectrum is obtained on a screen.
(a) Name the seven colours of the spectrum in order.
(b) Do the colours have the same width in the spectrum?
(c) which of the colour of the spectrum of white light deviates (i) the most, (ii) the least?

The wavelengths for the light of red and blue colours are roughly 7.8 × 10^7 m and 4.8 × 10^7 m respectively.
(a) Which colour has the greater speed in vacuum?
(b) Which colour has the greater speed in vacuum?

(i) Draw a diagram to show the splitting of white light by a prism into its constituent colour.
(ii) Draw another diagram to show how the colours of spectrum of white light can be combined
to give the effect of white light.

Complete the ray diagram given below to show the nature of light produced on the screen.

Name the subjective property of light related to its wavelength.

What is the range of wavelength of the spectrum of white light in (i) Å, (ii) nm?

Write the approximate wavelengths for (i) blue and (ii) red light.

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MULTIPLE CHOICE TYPE:

When a white light ray falls on a prism, the ray at its first surface suffers.
(a) no refraction
(b) only dispersion
(c) only deviation
(d) both deviation and dispersion

MULTIPLE CHOICE TYPE:

In the spectrum of white light by a prism, the colour at the extreme end opposite to the base of prism is:
(a) violet

(b) yellow
(c) red

(d) blue

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Calculate the frequency of yellow light of wavelength 550nm. The speed of light is 3×10^8m/s^-1

The frequency range of visible light is from 3.75 x 10^14 Hz to 7.5 x 10^14 Hz. Calculate its wavelength range. Take speed of light = 3 x 10^8m/s^-1

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(a) Give a list of at least five radiations, in order of their increasing frequencies, which make up the complete electromagnetic spectrum.
(b) Which of the radiation mentioned in answer to part (a) has the highest penetrating power?

Arrange the following radiations in the order of their increasing wavelength:
X-rays, infrared rays, ratio waves, gamma ray and micro waves?

Which radiation is used for satellite communication?

A wave has a wavelength of 0.01 Å of Name the wave.

A wave has a wavelength of 0.01 Å of State its one property different from light.

(a) Name the high energetic invisible electro-magnetic wave which helps in the study of structure of crystals.
(b) State one more use of the wave named in part (a).

What is the range of the wavelength of the following electromagnetic waves?
(a) Gamma rays.

What is the range of the wavelength of the following electromagnetic waves?

(a)X-rays,

What is the range of the wavelength of the following electromagnetic waves?

(a) Ultraviolet

What is the range of the wavelength of the following electromagnetic waves?

(a) Visible.

What is the range of the wavelength of the following electromagnetic waves?

(a) Infrared.

What is the range of the wavelength of the following electromagnetic waves?

(a) Micro waves .

What is the range of the wavelength of the following electromagnetic waves?

Give the range of wavelength of the electromagnetic waves visible to us.

Name the region beyond  the red end  of the spectrum.

Name the region beyond the violet end, of the spectrum.

What do you understand by the invisible spectrum? How will you investigate the existence of radiation beyond the red and violet ends of the spectrum?

State the approximate range of wavelength associated with  the ultraviolet rays .

State the approximate range of wavelength associated with  the visible light .

State the approximate range of wavelength associated with infrared rays.

Name the radiations of wavelength just  longer than 8 x 10^-7m .

Name the radiations of wavelength just Shorter than 4 x 10^-7 m.

Name two electromagnetic waves of frequency greater than that of violet light. State one use of each.

Give one use of  microwaves .

Give one use of ultraviolet radiations .

Give one use of infrared radiations .

Give one use of gamma rays.

Name the rays or waves  of highest frequency .

Name the rays or waves used for taking photographs in dark .

Name the rays or waves produced by the changes in the nucleus of an atom .

Name the rays or waves of wavelength nearly 0.1 nm.

Two waves A and B have wavelength 0.01 Å and 9000 Å respectively.
(a) Name the two waves.
(b) Compare the speeds of these waves when they travel in vacuum.

What are infrared radiations? How are they detected? State one use of these radiations.

What are ultraviolet radiations? How are they detected? State one use of these radiations.

Name three properties of ultraviolet radiations which are similar to visible light.

Give two properties of ultraviolet radiations which differ from the visible light.

Mention three properties of infrared radiations similar to the visible light.

Give two such properties of infrared radiations which are not true for visible light.

Infrared radiations are used for photography in fog.

Infrared radiations are used as signals during war

the photographic darkrooms are provided with infrared lamps.

A rock salt prism is used instead of a glass prism to obtain the infrared spectrum.

A quartz is required for obtaining the spectrum of the ultraviolet light.

Ultraviolet bulbs have a quartz envelope instead of glass

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MULTIPLE CHOICE TYPE:

The most energetic electromagnetic radiations are:
(a) Microwaves

(b) ultraviolet waves

(c) X-rays

(d) gamma rays

MULTIPLE CHOICE TYPE:

The source of ultraviolet light is:
(a) electric bulb

(b) red hot iron ball

(c) sodium vapour lamp

(d) carbon arc-lamp

MULTIPLE CHOICE TYPE:

A radiations A is focused by a proper device on the bulb of a thermometer. Mercury in the thermometer shows a rapid increase. The radiations A is:
(b) visible light
(d) X-rays

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An electromagnetic wave has a frequency of 500 MHz and a wavelength of 60 cm Calculate the velocity of the wave.

An electromagnetic wave has a frequency of 500 MHz and a wavelength of 60 cm.name the medium through which it is travelling

The wavelength of X-rays is 0.01 Å. Calculate its frequency.

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What is meant by scattering of light?

How does the intensity of scattered light depends on the wavelength of incident light? State conditions when this dependence holds.

When sunlight enters the earth’s atmosphere, state which colour of light is scattered the most and which the least.

The danger signal is red. Why?

How would the sky appear when seen from the space (or moon)? Give reason for your answer.

What characteristic property of light is responsible for the blue colour of the sky?

The colour of sky, in direction other than of the sun, is blue. Explain.

Why does the sun appear red at sunrises and sunset?

The sky at noon appears white. Give reason.

The clouds are seen white. Explain

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MULTIPLE CHOICE TYPE:

In white light of sun, maximum scattering by the air molecular present in the earth’s atmosphere is for:
(a) red colour (b) yellow colour
(c) green colour (d) blue colour

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