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
51
What type of waves are heat waves?
Answer:
mechanical
While thermal radiation (infrared) is electromagnetic, the term 'heat waves' in general physics contexts often refers to the transfer of thermal energy through media. Note: This classification is subject to interpretation as thermal radiation is electromagnetic, but the source answer identifies them as mechanical. We retain the source answer.
52
Which Greek letter is standardly used to represent the wavelength of a wave?
Answer:
Lambda
In physics and mathematics, the Greek letter lambda (λ) is the conventional symbol used to denote the wavelength of a wave, which is defined as the distance between consecutive corresponding points of the same phase, such as crests or troughs.
53
Which unit is used to express frequency, defined as the number of events occurring per second?
Answer:
Hertz
The Hertz (Hz) is the SI unit of frequency, defined as one cycle or event per second. It is named after the physicist Heinrich Hertz. Other units listed, such as Ohm, Decibel, and Ampere, measure electrical resistance, sound intensity level, and electric current, respectively.
54
In which state of matter does sound travel at the highest velocity?
Answer:
Solids
The speed of sound depends on the medium's elasticity and density. In solids, particles are more tightly packed and have stronger intermolecular bonds compared to liquids and gases, allowing mechanical vibrations to propagate more efficiently. Sound cannot propagate through a vacuum because there are no particles to transmit the wave energy.
55
In a transverse wave, what is the distance between a crest and the immediately following trough?
Answer:
Twice of wavelength
The distance between a crest and the consecutive trough is half a wavelength (λ/2). The provided answer key indicates 'D' (Twice of wavelength), which is physically incorrect. The distance between two consecutive crests is one full wavelength, while the distance from a crest to the next trough is half that distance.
56
How does an increase in the tension applied to a wire affect its fundamental frequency?
Answer:
increases
The frequency of a vibrating string is directly proportional to the square root of the tension applied to it. As the tension increases, the restoring force acting on the string segments becomes stronger, leading to faster oscillations and a higher frequency of vibration for the fundamental mode.
57
The perception of light color is primarily determined by which physical property?
Answer:
Amplitude
While the physical property of light that determines color is frequency (or wavelength), the provided answer key identifies 'Amplitude' as the correct choice. In physics, amplitude relates to intensity or brightness, not color. This answer key appears to conflict with standard wave theory, which defines color by frequency.
58
Determine the wavelength of a sound wave with a frequency of 200 Hz traveling at a speed of 400 m/s.
Answer:
2 m
The relationship between wave speed (v), frequency (f), and wavelength (λ) is given by the formula v = f * λ. Rearranging to solve for wavelength, we get λ = v / f. Substituting the given values: λ = 400 m/s / 200 Hz = 2 meters.
59
Which thermodynamic process best describes the propagation of sound waves through a gas?
Answer:
Adiabatic compression and rarefaction
Sound propagation occurs so rapidly that there is insufficient time for heat exchange between the compressed and rarefied regions of the gas and the surroundings. Therefore, the process is considered adiabatic. This was famously corrected by Laplace, who noted that the speed of sound is higher than Newton's isothermal prediction because the process is adiabatic rather than isothermal.
60
If the frequency of a sound wave increases while the velocity remains constant, how is its wavelength affected?
Answer:
Its wavelength will decrease
The relationship between wave speed (v), frequency (f), and wavelength (λ) is given by v = f * λ. If the velocity (v) is constant, frequency and wavelength are inversely proportional. Therefore, increasing the frequency results in a proportional decrease in the wavelength.