23 + Interview Questions in SPECTRUM IN GENERAL AWARENESS Page 1 InterviewSolution

1.	Give one use electromagnetic radiations in Microwaves.
Answer» Microwaves are used for communication.

Discussion

2.	State three properties of infra red radiations similar to that of visible light.
Answer» (i) Infrared radiations and visible light both travel in vacuum with a speed 3 × 10⁸ms^-1. (ii) Both the infra red radiations and the visible light obey the laws of reflection and refraction. (iii) Both the infra red radiations and the visible light are electromagnetic waves.

2.

State three properties of infra red radiations similar to that of visible light.

Answer»

(i) Infrared radiations and visible light both travel in vacuum with a speed 3 × 10⁸ms^-1.

(ii) Both the infra red radiations and the visible light obey the laws of reflection and refraction.

(iii) Both the infra red radiations and the visible light are electromagnetic waves.

Discussion

3.	Write three conditions necessary to obtain a pure spectrum on a screen. Name the instrument in which the conditions stated by you are fulfilled.
Answer» The three conditions necessary to obtain a pure spectrum on a screen are: (i) A narrow parallel beam of light should be made incident on the prism. (ii) The prism should be placed in the position of minimum deviation. (iii) The emergent parallel beam should be focussed on the screen. These conditions are fulfilled in spectrometer.

3.

Write three conditions necessary to obtain a pure spectrum on a screen. Name the instrument in which the conditions stated by you are fulfilled.

Answer»

The three conditions necessary to obtain a pure spectrum on a screen are:

(i) A narrow parallel beam of light should be made incident on the prism.

(ii) The prism should be placed in the position of minimum deviation.

(iii) The emergent parallel beam should be focussed on the screen. These conditions are fulfilled in spectrometer.

Discussion

4.	Distinguish between an impure spectrum and a pure spectrum.
Answer» A spectrum in which there is overlapping of different colours is called an impure Spectrum. In other words, in an impure spectrum, the colours are not distinct and independent but they overlap. On the other hand, a spectrum with each colour distinct and independent is called a pure spectrum.

Discussion

5.	State three properties of ultra-violet radiations similar to visible light.
Answer» (i) Ultra-violet radiations can travel in vacuum as the visible light can do, with the speed 3 × 10⁸ms^-1. (ii) Both the ultra-violet radiations and the visible light are electromagnetic waves. (iii) Both the ultra-violet radiations and the visible light obey the laws of reflection and refraction.

5.

State three properties of ultra-violet radiations similar to visible light.

Answer»

(i) Ultra-violet radiations can travel in vacuum as the visible light can do, with the speed 3 × 10⁸ms^-1.

(ii) Both the ultra-violet radiations and the visible light are electromagnetic waves.

(iii) Both the ultra-violet radiations and the visible light obey the laws of reflection and refraction.

Discussion

6.	State two properties of ultra-violet radiations which differ from visible light.
Answer» (i) Ultra-violet radiations are of wavelength shorter than that of visible light. (ii) Ultra-violet radiations are more chemically active than the visible light.

6.

State two properties of ultra-violet radiations which differ from visible light.

Answer»

(i) Ultra-violet radiations are of wavelength shorter than that of visible light.

(ii) Ultra-violet radiations are more chemically active than the visible light.

Discussion

7.	How can the presence of infrared Radiations be detected?
Answer» In presence of infra red radiations, the temperature recorded by a blackened bulb thermometer rapidly increases.

Discussion

8.	State two properties of ultra-violet radiations which differ from visible light.
Answer» (i) Ultra-violet radiations are of wavelength shorter than that of visible light. (ii) Ultra-violet radiations are more chemically active than the visible light.

8.

State two properties of ultra-violet radiations which differ from visible light.

Answer»

(i) Ultra-violet radiations are of wavelength shorter than that of visible light.

(ii) Ultra-violet radiations are more chemically active than the visible light.

Discussion

9.	Name the radiation of wavelength longer than 8 × 10-7m.
Answer» Infra red radiations.

Discussion

10.	Give one use electromagnetic radiations in Infrared radiation.
Answer» Infrared radiations are used as signals during war.

Discussion

11.	What effect do the ultra-violet radiations have on the human body?
Answer» The ultra-violet radiations cause skin diseases on the human body.

Discussion

12.	State two uses of infrared radiations.
Answer» (i) For therapeutic purpose. (ii) In night photography.

12.

State two uses of infrared radiations.

Answer»

(i) For therapeutic purpose.

(ii) In night photography.

Discussion

13.	What is the region beyond the violet end of spectrum called?
Answer» Ultra-violet region.

Discussion

14.	Give one use of Infrared radiations.
Answer» Infrared radiations are used in remote control of television.

Discussion

15.	Name the radiations that are used for photography at night.
Answer» Infrared radiations.

Discussion

16.	Name the radiations used for detection of fracture in bones.
Answer» X-rays used for detection of fracture in bones.

Discussion

17.	An imaginary material reflects red light, scatters green light, transmits blue light and absorbs yellow, orange and violet light. A cube of this material is shown in the given diagram. The surface is illuminated with a beam of white light. What colour will this cube appear (i) from above, (ii) from below and (iii) from the sides?
Answer» When viewed from above — Red. When viewed from above — Blue. When viewed from above — Green.

17.

An imaginary material reflects red light, scatters green light, transmits blue light and absorbs yellow, orange and violet light. A cube of this material is shown in the given diagram. The surface is illuminated with a beam of white light. What colour will this cube appear (i) from above, (ii) from below and (iii) from the sides?

Answer»

When viewed from above — Red.

When viewed from above — Blue.

When viewed from above — Green.

Discussion

18.	What is understood by the term dispersion of light? What is its cause?
Answer» The splitting of white light into its constituents colours when white light passes through a prism, is called dispersion of light. The cause of dispersion is the deviation of light of different colours through different angles, by a prism.

Discussion

19.	Which colour of white light is deviated most.
Answer» The violet is deviated most.

Discussion

20.	Give reason, why violet colour of white light deviated most and red colour of white light deviated least.
Answer» The reason is that the speed of violet light in glass is least while that of red light is most. Since. Referective index of glass = speed of light in air/speed of light in glass, so the refractive index of glass (the material of prism) is most for violet light and least for red light. Hence, the violet light is deviated most and red light is deviated least.

Discussion

21.	Write approximate wavelength for (i) blue (ii) red light. Which colour has the higher speed in vacuum? Which colour has the higher speed in glass?
Answer» (i) The wavelength of blue light is nearly 4600Å. (ii) The wavelength of red light is nearly 7900Å. Both colours have the same speed in vacuum. Red light has the higher speed in glass.

21.

Write approximate wavelength for (i) blue (ii) red light. Which colour has the higher speed in vacuum? Which colour has the higher speed in glass?

Answer»

(i) The wavelength of blue light is nearly 4600Å.

(ii) The wavelength of red light is nearly 7900Å.

Both colours have the same speed in vacuum. Red light has the higher speed in glass.

Discussion

22.	Which colour of white light is deviated least.
Answer» The red light is deviated least.

Discussion

23.	In the atmosphere which colour of light gets scattered the least?
Answer» In atmosphere red colour scatters the least.

Discussion

Explore topic-wise InterviewSolutions in .

Give one use electromagnetic radiations in Microwaves.

State three properties of infra red radiations similar to that of visible light.

Write three conditions necessary to obtain a pure spectrum on a screen. Name the instrument in which the conditions stated by you are fulfilled.

Distinguish between an impure spectrum and a pure spectrum.

State three properties of ultra-violet radiations similar to visible light.

State two properties of ultra-violet radiations which differ from visible light.

How can the presence of infrared Radiations be detected?

State two properties of ultra-violet radiations which differ from visible light.

Name the radiation of wavelength longer than 8 × 10-7m.

Give one use electromagnetic radiations in Infrared radiation.

What effect do the ultra-violet radiations have on the human body?

State two uses of infrared radiations.

What is the region beyond the violet end of spectrum called?

Give one use of Infrared radiations.

Name the radiations that are used for photography at night.

Name the radiations used for detection of fracture in bones.

What is understood by the term dispersion of light? What is its cause?

Which colour of white light is deviated most.

Give reason, why violet colour of white light deviated most and red colour of white light deviated least.

Write approximate wavelength for (i) blue (ii) red light. Which colour has the higher speed in vacuum? Which colour has the higher speed in glass?

Which colour of white light is deviated least.

In the atmosphere which colour of light gets scattered the least?