Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
11
How does the velocity of laser light compare to that of ordinary light?
Answer:
Equal to ordinary light
Laser light is electromagnetic radiation, just like ordinary light. According to the principles of physics, all electromagnetic waves travel at the same constant speed, denoted as 'c' (the speed of light in a vacuum), regardless of their source, coherence, or intensity.
12
What are the defining characteristics of a laser beam in terms of wave properties?
Answer:
Coherent and monochromatic
Laser stands for Light Amplification by Stimulated Emission of Radiation. A laser beam is characterized by coherence, meaning the light waves are in phase with each other, allowing for constructive interference and high intensity. It is also monochromatic, meaning it consists of a single, specific wavelength or color. These properties distinguish laser light from ordinary light sources, which are typically incoherent and polychromatic.
13
What term describes the state in which a higher energy level contains more atoms than a lower energy level?
Answer:
Inverted population
Population inversion is a non-equilibrium condition where the number of atoms in an excited state exceeds the number in a lower energy state. This is a fundamental requirement for laser action, as it ensures that stimulated emission dominates over absorption.
14
What interaction occurs when high-energy photons strike an object in its ground energy state?
Answer:
Absorbed
When an atom is in its ground state, it has the lowest possible energy. If a photon with sufficient energy strikes the atom, the atom will absorb the photon, causing an electron to jump to a higher energy level. This process is known as absorption, which is the opposite of stimulated emission.
15
In a laser, such as a neon laser, what characteristics do the emitted light waves share?
Answer:
All of these
Laser light is characterized by being monochromatic (same frequency/wavelength), coherent (same phase relationship), and collimated. These properties arise from the process of stimulated emission, where photons are emitted in a synchronized manner, resulting in a highly ordered beam of light.