Practice MCQ Questions and answers on Physics-GK

In a Laser all the atoms emit the light waves of same frequency, amplitude and phase. A laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons. The term “laser” originated as an acronym for Light Amplification by Stimulated Emission of Radiation.

Laser, an acronym for Light Amplification by Stimulated Emission of Radiation, creates a radiation beam that is coherent (in-phase). In a coherent light source, the amplitude of the radiated waves is added and results in a radiation beam of great intensity. It normally produces only one or two wavelengths. The single wavelength is called monochromatic radiation.

In quantum mechanics a particle is represented by a Wave packet.

The P wave indicates atrial depolarization. The P wave occurs when the sinus node, also known as the sinoatrial node, creates an action potential that depolarizes the atria. The P wave should be upright in lead II if the action potential is originating from the SA node.

The polarization phenomenon, verifies the transverse nature of light.

The polarization phenomenon, verifies the transverse nature of light.

When a ray of light falls on sea shell, then its small amount first gets refracted (slightly polarised) and then almost gets reflected back (fully polarised). That is why, view of sea shell is golden due to polarisation.

The light of distant stars is affected by interstellar dust and the Earth's atmosphere.

The iridescent colours of soap bubbles are caused by interfering of (internally and externally) reflected light waves and are determined by the thickness of the film. This phenomenon is not the same as the origin of rainbow colours (caused by the refraction of internally reflected light), but rather are the same as the phenomenon causing the colours in an oil slick on a wet road. As light impinges on the film some of it reflects off of the outer surface, some of it enters the film and reemerges after reflecting off the second surface, some of it enters the film and reemerges after bouncing back and forth between the two surfaces from 1 to n times. The total reflection observed is determined by the interference of all these reflections.

Only transverse waves (such as radio, ultraviolet and infrared waves) can be polarized since their vibrations can potentially occur in all directions perpendicular to the direction of travel. It is therefore possible to confine the vibrations to a single plane. However, sound waves are longitudinal in which vibrations are parallel to the direction of travel of the wave. The vibrations of a longitudinal wave occur along a single line, it is therefore not possible to confine that to a plane. So it cannot be polarized.