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प्रश्न
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उत्तर
The electromagnetic radiations of wavelength from 100 Å to 4000 Å are called the ultraviolet radiations.
Detection: If the different radiations from the red part of the spectrum to the violet end and beyond it are made incident on the silver-chloride solution, it is observed that from the red end to the violet, the solution remains almost unaffted. However just beyond the violet end, it first turns violet and finally it becomes dark brown (or black). thus, there exist certain radiations beyond the violet end of the spectrum, which are chemically more active than the visible light. Thses radiations are called the ultraviolet radiations.
Two properties of ultraviolet radiation:
1. Ultraviolet radiation can pass through quartz, but they are absorbed by glass.
2. They are usually scattered ny the dust particles present in the atmosphere.
one use of ultraviolet radiation:
in producing, Vitamin D, in food of plans and animals.
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संबंधित प्रश्न
Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 cm (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 MHz (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).
(c) 2.7 K [temperature associated with the isotropic radiation filling all space-thought to be a relic of the ‘big-bang’ origin of the universe].
(d) 5890 Å - 5896 Å [double lines of sodium]
(e) 14.4 keV [energy of a particular transition in 57Fe nucleus associated with a famous high resolution spectroscopic method (Mössbauer spectroscopy)].
A wave has a wavelength of 10-3 nm. Name the wave.
What is the range of the wavelength of the following electromagnetic waves?
(a) Gamma rays.
Give one use of microwaves.
X-ray incident on a material
(a) exerts a force on it
(b) transfers energy to it
(c) transfers momentum to it
(d) transfers impulse to it.
The distance between the cathode (filament) and the target in an X-ray tube is 1.5 m. If the cutoff wavelength is 30 pm, find the electric field between the cathode and the target.
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
The electron beam in a colour TV is accelerated through 32 kV and then strikes the screen. What is the wavelength of the most energetic X-ray photon?
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
Light of wavelength `3500A` is incident on two metals A and B whose work functions are 3.2 eV and 1.9 eV respectively. Which metal will emit photoelectrons?
Identify the electromagnetic wave whose wavelength range is from about 10-12 m to about 10-8 m. Write one use of this.
Below is an incomplete table showing the arrangement of electromagnetic spectrum in the increasing order of their wavelength. Complete the table:
| Gamma ray | X - ray | UV rays | Visible rays | Infrared | A | Radio waves |
- Identify the radiation A.
- Name the radiation used to detect fracture in bones.
- Name one property common to both A and Radio waves.
