Physics MCQs

Notes:
The Corpuscular theory of light was given by Isaac Newton. It was replaced by Huygens’ wave theory when it failed to adequately explain the diffraction, interference and polarization of light. The Huygens’ wave theory was replaced by Planck’s quantum theory and finally de-Broglie’s Dual-Theory of light replaced all previous ones.

Notes:
J.J Thompson was the first scientist to discover and identify the electrons and to make the discovery of the first subatomic particle. He was also the first scientist to find evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles led to the development of the mass spectrograph. J.J Thompson belonged to United Kingdom. He won the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases.

Notes:
Sidereal day is the time taken by the earth to complete one rotation about its axis w.r.t a fixed star Solar day is the time taken by the earth to complete one rotation about its axis w.r.t the sun. Shake is the smallest practical unit of time 1 shake = 10^-8s Tropical year: The year in which there is a total solar eclipse.

Notes:
The conditions for equilibrium for an object: 1. There is no linear motion of the object i.e. the resultant force on the object is zero 2. There should not be any rotational motion of the object i.e. the torque on the object should be zero 3. The potential energy of the object should be minimum for stable equilibrium.

Notes:
The velocity of rocket at any time is directly proportional to the exhaust speed of the gases and to the natural log of ratio of intial mass of rocket to its mass at that instant. V = u log(m1/m2)

Notes:
Electron volt is a practical unit of energy. Some practical units of energy are: 1 erg = 10^-7 J 1 calorie = 4.2 J 1 Kilowatt hour = 3.6 x 10⁶ J 1 Electron volt(ev) = 1.6 x 10^-19 J

Notes:
The energy by virtue of its position is known as Potential energy. The energy by virtue of its motion is known as Kinetic energy.

Notes:
A second’s pendulum, also known as a seconds pendulum, is defined as a pendulum whose period of oscillation is precisely two seconds, one second for a swing in one direction and one second for the return swing, a frequency of 1/2 Hz. It was once used to define the second of time.

Notes:
The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time. It is represented by s = wavelength x frequency.

Notes:
The speed of sound decreases when we go from solid to gaseous state.