Please select a subject first
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Why are traffic signals red in colour?
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When a sound wave travels through air, the air particles ______.
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The sound waves are reflected from an obstacle into the same medium from which they were incident. Which of the following changes?
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Rapid back and forth motion of a particle about its mean position is called _____.
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If the energy in a longitudinal wave travels from south to north, the particles of the medium would be vibrating in _____.
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Sound can travel through solids, gases, liquids, and even vacuum.
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Waves created by Earth Quake are Infrasonic.
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Match the following
| 1. | Infrasonic | (a) | Compressions |
| 2. | Echo | (b) | 22 kHz |
| 3. | Ultrasonic | (c) | 10 Hz |
| 4. | High-pressure region | (d) | Ultrasonography |
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Name three animals, which can hear ultrasonic vibrations.
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Why does an empty vessel produce more sound than a filled one?
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Mention two cases in which there is no Doppler effect in sound?
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Two observers are stationed in two boats 4.5 km apart. A sound signal sent by one, under water, reaches the other after 3 seconds. What is the speed of sound in the water?
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Name three animals which can hear ultrasonic vibrations.
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Suppose that a sound wave and a light wave have the same frequency, then which one has a longer wavelength?
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Unit of radioactivity is _______
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Which of the following statements is/are correct?
- α particles are photons
- Penetrating power of γ radiation is very low
- Ionization power is maximum for α rays
- Penetrating power of γ radiation is very high
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88Ra226 experiences three α - decay. Find the number of neutrons in the daughter element.
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Match the following
| Column A | Column B | |
| a) | Atavism | caudal vertebrae and vermiform appendix |
| b) | Vestigial organs | a forelimb of a cat and a bat’s wing |
| c) | Analogous organs | rudimentary tail and thick hair on the body |
| d) | Homologous organs | a wing of a bat and a wing of an insect |
| e) | Wood park | radiocarbon dating |
| f) | W.F. Libby | Thiruvakkarai |
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