Physics MCQs

Notes:
The latent heat Latent heat is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process. It causes change in state or phase but not in temperature.

Notes:
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz to as low as 30 hertz. It is used to measure the speed of an approaching car.

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This question is related to Antoine equation. Water to get boil, its vapour pressure must reach to its surrounding pressure. In a pressure cooker, it boils at the highest temperature. Elevation of Kochi is 0 m, ooty is 2,486 m, Mount Abu is 1,200 m, New Delhi is 216 m, Shimla is 2,205 m. So comparing all of them, water will boil at lowest temperature at ooty, followed by Shimla, Mount Abu , New Delhi and Kochi. This is because , higher we go lower is the atmospheric pressure and lower is the point where water`s vapour pressure gets equal to the atmospheric pressure.

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To hear an echo, the minimum distance between a wall and the source of sound is 17m. The minimum interval is 0.1 sec.

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Quartz crystals have piezoelectric properties: they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. A common piezoelectric use of quartz today is as a crystal oscillator. The quartz clock is a familiar device using the mineral. Quartz is also strongly pyroelectric. Temperature changes create positive and negative charges within the crystal.

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An Electric generator works on the principle of Faraday’s law of Electromagnetic Induction. An electric generator uses mechanical energy to generate electricity applying Faraday’s law of induction. It spins a coil at a constant rate in a magnetic field to induce an oscillating emf.

Notes:
In the presented choices, the Fermi stands as the smallest unit of length measurement. It is equal to 10^-15 m. Comparatively, 1 Micron equals 10^-6 m, 1 Nanometer equals 10^-9 m, and 1 Angstrom equivalent to 10^-10 m. All these units are commonly used to measure minuscule distances, particularly in the realm of nanotechnology and particle physics. However, the Fermi, named after the esteemed physicist Enrico Fermi, remains the smallest.

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The unit of Velocity Gradient is s^-1(per second) Velocity Gradient = Velocity/time Velocity gradient shows that how the velocity of a fluid changes between different points within the fluid.

Notes:
Joule is the absolute unit of work in S.I 1 joule = 1 Nm

• 1 joule= 10⁷ ergs (erg is the unit of work in c.g.s)
• 1 erg = 1 dyne cm
• Also, Kilogram-metre (kg-m) is the gravitational unit of work on S.I 1 kg-m = 9.8 j

Notes:
Work done will be zero: 1. When displacement is zero 2. When force is zero 3. When angle between force and displacement vector is zero