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
How are infrared waves produced?
Identify the part of the electromagnetic spectrum which is suitable for radar system used in aircraft navigation.
Why are infra-red waves often called heat waves? Explain.
What is the range of the wavelength of the following electromagnetic waves?
(a)X-rays,
What is the range of the wavelength of the following electromagnetic waves?
(a) Infrared.
Two waves A and B have wavelength 0.01 Å and 9000 Å respectively.
- Name the two waves.
- Compare the speeds of these waves when they travel in vacuum.
Name two sources, each of infrared radiations and ultraviolet radiations.
What are ultraviolet radiations?
The energy of a photon of a characteristic X-ray from a Coolidge tube comes from
X-ray from a Coolidge tube is incident on a thin aluminium foil. The intensity of the X-ray transmitted by the foil is found to be I0. The heating current is increased to increase the temperature of the filament. The intensity of the X-ray transmitted by the foil will be
(a) zero
(b) < I0
(c) I0
(d) > I0
The Kα X-rays of aluminium (Z = 13) and zinc (Z = 30) have wavelengths 887 pm and 146 pm respectively. Use Moseley's law √v = a(Z − b) to find the wavelengths of the Kα X-ray of iron (Z = 26).
(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)
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.)
Calculate the shortest wavelength of electromagnetic radiation present in Balmer series of hydrogen spectrum.
Name two sources of ultraviolet radiation.
Choose the correct option.
Earth’s atmosphere is richest in
Answer briefly.
Why light waves travel in a vacuum whereas sound waves cannot?
What are the ultraviolet rays?
Answer briefly.
What is a carrier wave?
Calculate the wavelength of a microwave of a frequency of 8.0 GHz.
An e.m. wave exerts pressure on the surface on which it is incident. Justify.
Which of the following is a tool used for separating the different color wavelengths from each other?
Find the photon energy in units of ev for electromagnetic wave if waves length 40 m. Given h = 6.63 × 10–34 J.
A radio can tune to any station in the 7.5 mHz to 12 MHz band. What is corresponding wave length band.
Radio waves of constant amplitude can be generated with.
SONAR emits which of the following waves?
The magnetic field of a beam emerging from a filter facing a floodlight is given by B0 = 12 × 10–8 sin (1.20 × 107z – 3.60 × 1015t) T. What is the average intensity of the beam?
What happens to the intensity of light from a bulb if the distance from the bulb is doubled? As a laser beam travels across the length of a room, its intensity essentially remains constant. What geometrical characteristic of LASER beam is responsible for the constant intensity which is missing in the case of light from the bulb?
Electromagnetic waves of wavelengths λ1, λ2 and λ3 are used in a radar system, in water purifiers and in remote switches of TV, respectively.
- Identify the electromagnetic waves.
- Write one source for each of them.
