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प्रश्न
Answer briefly.
Why high-frequency carrier waves are used for the transmission of audio signals?
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उत्तर
An audio signal has a low frequency (< 20 kHz) and low-frequency signals cannot be transmitted over large distances. Because of this, high-frequency carrier waves are used for transmission.
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संबंधित प्रश्न
Why are microwaves considered suitable for radar systems used in aircraft navigation?
How are infrared waves produced?
To which part of the electromagnetic spectrum does a wave of frequency 5 × 1011 Hz belong?
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)].
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(a) Which colour has the greater speed in vacuum?
(b) Which colour has the greater speed in glass?
What is the range of the wavelength of the following electromagnetic waves?
(a) Micro waves .
Give the range of wavelength of the electromagnetic waves visible to us.
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The figure shows the intensity-wavelength relations of X-rays coming from two different Coolidge tubes. The solid curve represents the relation for the tube A in which the potential difference between the target and the filament is VA and the atomic number of the target material is ZA. These quantities are VB and ZB for the other tube. Then,
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(b) K X-ray is emitted when a hole makes a jump from the K shell to some other shell.
(c) The wavelength of K X-ray is smaller than the wavelength of L X-ray of the same material.
(d) The wavelength of Kα X-ray is smaller than the wavelength of Kβ X-ray of the same material.
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| Element | Ne | P | Ca | Mn | Zn | Br |
| Energy (keV) | 0.858 | 2.14 | 4.02 | 6.51 | 9.57 | 13.3 |
Write the range of the wavelength of the following electromagnetic radiations:
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(c) γ -rays
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