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
71
What is the approximate wavelength range of the visible light spectrum?
Answer:
3900 – 7600 angstrom
The visible spectrum is the portion of the electromagnetic spectrum that the human eye can perceive. This range spans from approximately 390 nanometers (violet light) to 760 nanometers (red light). Since 1 nanometer equals 10 angstroms, this corresponds to a range of 3900 to 7600 angstroms. This range is critical for optical physics and the study of light interaction with matter.
72
What is the primary physical reason for the blue appearance of the sea?
Answer:
Reflection of sky and scattering of light by the drops of water
The blue color of the sea is primarily due to the scattering of sunlight by water molecules and suspended particles, combined with the reflection of the blue sky. While water absorbs longer wavelengths (red/yellow) more strongly, the scattering of shorter blue wavelengths contributes significantly to the observed color.
73
Which specific type of glass is engineered to effectively absorb or block ultraviolet radiation?
Answer:
Crookes Glass
Crookes glass is a type of glass containing cerium and other rare earth elements, which gives it the property of absorbing ultraviolet light while remaining transparent to visible light. It was historically used in the manufacturing of sunglasses and protective eyewear to shield the eyes from harmful UV radiation.
74
Which color is considered the complementary color of yellow?
Answer:
Blue
In the context of color theory and additive color mixing, complementary colors are pairs that, when combined or mixed in the right proportions, produce a neutral color like white or gray. For the color yellow, which is a primary color in subtractive mixing but a secondary color in additive mixing, blue is identified as its complementary color on the standard color wheel.
75
Why are radio telescopes considered superior to optical telescopes for certain astronomical observations?
Answer:
All of the above
Radio telescopes offer significant advantages over optical telescopes. They can penetrate clouds and atmospheric interference, operate continuously during both day and night, and detect celestial objects, such as faint galaxies or pulsars, that do not emit significant visible light but emit strong radio waves.
76
Which of the following statements regarding the wavelength of visible light is correct?
Answer:
Wavelength of red light is more than violet light
In the visible spectrum, red light has the longest wavelength (approximately 620-750 nm), while violet light has the shortest wavelength (approximately 380-450 nm). Therefore, the wavelength of red light is significantly greater than that of violet light.
77
What is the primary cause of light diffusion within the Earth's atmosphere?
Answer:
Dust particles
Light diffusion, or scattering, in the atmosphere is primarily caused by particles that are comparable in size to the wavelength of light. Dust particles, along with air molecules and water droplets, act as scattering centers for sunlight.
78
Which of the listed electromagnetic radiations possesses the longest wavelength?
Answer:
Infrared radiation
In the electromagnetic spectrum, wavelength is inversely proportional to frequency and energy. Among the choices provided, X-rays have the shortest wavelength and highest energy, followed by ultraviolet and visible light. Infrared radiation occupies the region of the spectrum with lower frequencies than visible light, and therefore, it has the longest wavelength of the options listed.
79
What is the full form of the acronym CFL, commonly used for energy-efficient lighting?
Answer:
Compact Fluorescent Lamp
CFL stands for Compact Fluorescent Lamp. These are gas-filled tubes that use electricity to excite mercury vapor, which produces ultraviolet light that is then converted into visible light by a phosphor coating.
80
What is the standard value for the speed of light in a vacuum?
Answer:
3 × 108ms-1
The speed of light in a vacuum is a fundamental physical constant, denoted by 'c'. Its exact value is 299,792,458 meters per second, which is commonly approximated as 3 × 10^8 meters per second for most physics calculations and general scientific applications.