Physics MCQs

Notes:
The correct answer is Quantum Theory. Black body radiation refers to the electromagnetic radiation emitted by an idealized object that absorbs all incident radiation. Max Planck introduced the concept in 1900, leading to the development of quantum mechanics. This theory explains that energy is quantized, emitted in discrete packets called quanta or photons, resolving the ultraviolet catastrophe predicted by classical physics.

Notes:
Voltmeter is an instrument for measuring electric charge or electrical potential difference. It was invented by Hans Christian Oersted.

Notes:
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.

Notes:
Gamma rays is commonly used in gemstone industry to change white topaz into blue topaz. Because white topaz is heat-treated to turn into blue topaz, the value of blue topaz is often decreased.

Notes:
Alpha radiation is not used in radiotherapy because it cannot penetrate human skin. Alpha particles are a highly ionizing form of particle radiation with a short range. They can be stopped by a few centimeters of air or by skin. This means that external therapy would be useless because the alpha radiation would not be able to enter the body.  Alpha particles have a very large atomic volume. They are given additional mass by the two neutrons they contain. This facilitates ionization by coulombic interaction or direct collision of the alpha particle with atomic electrons.  Radiation therapy is a treatment that uses ionizing radiation to kill or control the growth of malignant cells. It is often delivered by a linear particle accelerator.

Notes:
The range of the tera hertz radiation frequency is from roughly 0.1 THz to 10 THz. It is higher than the frequency of radio waves and microwaves, but lower than the frequency of infrared light.

Notes:
A CD or DVD has closely spaced tracks which work as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.

Notes:
Reynold Number has no units. The Reynolds number is the ratio of inertial forces to viscous forces. It is used for predicting if a flow condition will be laminar or turbulent.

• Unit of Rydberg constant: m^-1
• Unit of Wave number = m^-1
• Unit of Hubble constant = sec^-1

Notes:
The curie is a unit of ionizing radiation (radioactivity). It is symbolized with Ci . 1 curie = 3.7 x 10 10 disintegrations or nuclear transformations per second. This is approximately the amount of radioactivity emitted by one gram (1 g) of radium-226. The unit is named after Pierre Curie, a French physicist.

Notes:
The acceleration of an object at a given instant of time is called Instantaneous acceleration. When an object moves with variable acceleration, then it possesses different acceleration at different point of time.