Advertisements
Advertisements
प्रश्न
Answer briefly.
Why high-frequency carrier waves are used for the transmission of audio signals?
Advertisements
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.
APPEARS IN
संबंधित प्रश्न
What physical quantity is the same for X-rays of wavelength 10−10 m, red light of wavelength 6800 Å and radiowaves of wavelength 500 m?
Use the formula λm T= 0.29 cm K to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?
A wave has wavelength 50 Å.
- Name the wave.
- State its speed in vacuum.
- State its one use.
Name the subjective property of light related to its wavelength.
(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 by you in part (a) has the highest penetrating power.
Which radiation is used for satellite communication?
What is the range of the wavelength of the following electromagnetic waves?
(A) Radio waves.
Name the radiations of wavelength just shorter than 4 × 10-7 m.
Give one use of microwaves.
Name the waves used for taking photographs in dark.
When a Coolidge tube is operated for some time it becomes hot. Where does the heat come from?
Can a hydrogen atom emit characteristic X-rays?
Moseley's Law for characteristic X-ray is √v = a(Z − b). Here,
Frequencies of Kα X-rays of different materials are measured. Which one of the graphs in the figure may represent the relation between the frequency v and the atomic number Z ?

The X-ray beam emerging from an X-ray tube
Find the maximum potential difference which may be applied across an X-ray tube with tungsten target without emitting any characteristic K or L X-ray. The energy levels of the tungsten atom with an electron knocked out are as follows.
| Cell containing vacancy | K | L | M |
| Energy in keV | 69.5 | 11.3 | 2.3 |
Write the range of the wavelength of the following electromagnetic radiations:
(a) Infrared rays
(b) Ultraviolet rays
(c) γ -rays
Write one use of each of the above.
Name the radiation which can be detected by thermopile.
How will you investigate the existence of the radiation beyond the red and violet extremes of the spectrum?
Name the radiations used for the detection of fracture in bones.
Answer briefly.
Name the most harmful radiation entering the Earth's atmosphere from outer space.
Solve the numerical problem.
Calculate the wavelength in nm of an X-ray wave of frequency 2.0 × 1018 Hz.
A bat moving at 10 ms−1 towards a wall sends a sound signal of 8000 Hz towards it. On reflection, it hears a sound of frequency f The value of f in Hz is close to (speed of sound = 320 ms−1)
Which of the following is a tool used for separating the different color wavelengths from each other?
The frequency of x-rays, y-rays and ultraviolet rays are respectively a, b and c. Then:-
The frequency of e. m waves which is best suited .to observed of radius 3 × 10–4 his of the order of
The electric field intensity produced by the radiations coming from 100 W bulb at a 3 m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is ______.
Electromagnetic waves with wavelength
- λ1 is suitable for radar systems used in aircraft navigation.
- λ2 is used to kill germs in water purifiers.
- λ3 is used to improve visibility in runways during fog and mist conditions.
Identify and name the part of the electromagnetic spectrum to which these radiations belong. Also arrange these wavelengths in ascending order of their magnitude.
Write two uses of the following radiation.
X-rays
Which one of the following electromagnetic radiation has the least wavelength?
