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प्रश्न
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उत्तर
| Electromagnetic waves | Mechanical waves |
| 1. They can travel in vacuum. | 1. They cannot travel in vacuum. They need a materia I medium for their propagation. |
| 2. These are formed by the periodic vibrations of mutually perpendicular electric and magnetic field in a plane normal to the direction of wave propagation. | 2. These are formed by the vibrations of the medium particles about their mean positions. These vibrations can be along the direction of propagation of wave or perpendicular to it.. |
| 3. These are traverse in nature. | 3. These waves can be transverse as well as IonqitudnaI. |
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संबंधित प्रश्न
Define wavelength term in relation to a wave.
Define wave velocity term in relation to a wave.
What is the condition necessary for an echo to be heard distinctly?
What adjustments would you make for tuning a stringed instrument for it to emit a note of a desired frequency?
What is a megaphone ? Name the principle on which a megaphone works.
A type of electromagnetic wave has a wavelength of 50 Å. Name the wave and state one use of this type of wave.
Why is an echo not heard when the distance between the source of sound and reflection body is less than 10 m?
(i) A man stands at a distance of 68 m from a cliff and fires a gun. After what time interval will he hear the echo, if the speed of sound in air is 340 ms−1?
(ii) If the man had been standing at a distance of 12 m from the cliff would he have heard a clear echo?
Match the following:
| 1. | Stethoscope | a. | Repeated reflections |
| 2. | Echogram | b. | Multiple reflections |
| 3. | SONAR | c. | Ultrasonic waves |
| 4. | Reverberation | d. | Speed of underwater objects |
