Physics MCQs

Notes:
Force is the mass of an object, multiplied by its acceleration. If F is force, m is mass and a is acceleration, it can be expressed as: F = ma, or, a = F/m According to the question, m= 3 kg and F = 6 N So, a=6/3= 2 m/sec².

Notes:
A black body is an idealized physical body that absorbs all the incident electromagnetic radiation, regardless of frequency or angle of incidence. Another property is roughness. For example, sand is rough and black and so it is a good absorber of radiation.

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Materials for rain proof coats and tents owe their water proof properties to surface tension. The surface of a liquid behaves like an elastic membrane and therefore, has a tendency to contract. This property of liquid is called surface tension.

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In a water lifting electric pump, we convert electrical energy into potential energy. In hydraulic pump, mechanical energy is converted into potential energy.

Notes:
According to the Principle of floatation, when a body is immersed in a fluid, two forces act on it: (1) The weight of the body acting vertically downward through the centre of gravity of the body, and (2) The upthrust of the fluid acting vertically upward through the centre of gravity of the fluid displaced, i. e. , centre of buoyancy. The upthrust is also termed as buoyant force. (Archmides principle).

Notes:
The energy of a wave is proportional to the square of its amplitude. Therefore, the intensity of a wave is also proportional to the square of its amplitude. This means that if intensity drops off at a rate of 1/r2, wave amplitude drops off at a rate of 1/r.

Notes:
A spring scale or spring balance or Newton meter is a type of weighing scale. It consists of spring fixed at one end with a hook to attach an object at the other. It works by Hooke’s Law, which states that the force needed to extend a spring is proportional to the distance that spring is extended from its rest position.

Notes:
Scintillation or twinkling is generic terms for variations in apparent brightness or position of a distant luminous object viewed through a medium. One of the three principal factors governing astronomical seeing, atmospheric scintillation is defined as variations in illuminance only. Scintillation does not cause images of planets to flicker. Most scintillation effects are caused by anomalous refraction caused by small-scale fluctuations in air density usually related to temperature gradients.

Notes:
When a ray of light incident on a boundary separating two media comes back into the same media, this phenomenon, is called reflection of light. After reflection velocity, wavelength and frequency of light remains same but its only the intensity that decreases.

Notes:
The phenomena such as interference, diffraction, and polarization can only be explained when light is treated as a wave whereas photoelectric effect, line spectra, and the production and scattering of x rays demonstrate the particle nature of light. The photoelectric effect supports a particle theory of light in that it behaves like an elastic collision (one that conserves mechanical energy) between two particles, the photon of light and the electron of the metal.