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प्रश्न
The phenomena involved in the reflection of radiowaves by ionosphere is similar to ______.
पर्याय
reflection of light by a plane mirror.
total internal reflection of light in air during a mirage.
dispersion of light by water molecules during the formation of a rainbow.
scattering of light by the particles of air.
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उत्तर
The phenomena involved in the reflection of radiowaves by ionosphere is similar to total internal reflection of light in air during a mirage.
Explanation:
Radio waves are reflected by a layer of the atmosphere called the Ionosphere, so they can reach distant parts of the Earth. The reflection of radio waves by ionosphere is due to total internal reflection. It is the same as total internal reflection of light in the air during a mirage, i.e., angle of incidence is greater than critical angle.
Important point: The ionized part of the Earth’s atmosphere is known as the ionosphere. Ultraviolet light from the sun collides with atoms in this region knocking electrons loose. The creates ions or atoms with missing electrons. This is what gives the Ionosphere its name- and it is the free electrons that cause the reflection and absorption of ratio waves.
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संबंधित प्रश्न
State the conditions required for total internal reflection of light to take place
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index`3/2`, placed in water of refractive index `4/3`.Will this ray suffer total internal reflection on striking the face AC? Justify your answer.
State two conditions necessary for total internal reflection to occur.
The observation made by Swarali while doing the experiment is given below. Based on these write answers to the questions:
Swarali found that the light ray travelling from the denser medium to rarer medium goes away from the normal. If the angle of incidence (i) is raised by Swarali, the angle of refraction (r) went on increasing. However, after certain value of the angle of incidence the light ray is seen to return back into the denser medium.
Questions:
- What is the specific value of∠i called?
- What is the process of reflection of incident rays into denser medium called?
- Draw the diagrams of three observations made by Swarali.
Plot a graph between
Angle of incidence versus angle of refraction.
Name the principle on the basis of which optical fibres work.
How does a ray of light bend when it travels from rarer to denser medium
How does a ray of light bend when it travels from denser to rarer medium.
Can light be ‘piped’ like sound in a doctor’s stethoscope?
Express the refractive index μ of a medium in terms of the angle of incidence i in air and the angle of refraction r in a denser medium.
Draw a diagram, properly labelled, to illustrate the use of a total reflecting prism (a right-angled isosceles prism) to turn a ray of light through 180°. Name an instrument in which this device is used.
A ray of light passes through a right-angled prism as shown in the figure. State the angles of incidence at the faces AC and BC.
Choose the correct option.
Consider the following phenomena/ applications: P) Mirage, Q) rainbow, R) Optical fibre and S) glittering of a diamond. Total internal reflection is involved in
Describe the construction and working of an optical fibre.
Solve Numerical example.
A monochromatic ray of light is incident at 37° on an equilateral prism of refractive index 3/2. Determine angle of emergence and angle of deviation. If angle of prism is adjustable, what should its value be for emergent rays to be just possible for the same angle of incidence?
A bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
Write any two uses of total internal reflection.
A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5° and the prism is made of a material of refractive index 1.5, the angle of incidence is ______.
A ray of light passes through a prism of refractive index `sqrt2` as shown in the figure. Find:
- The angle of incidence (∠r2) at face AC.
- The angle of minimum deviation for this prism.
