Q61. Sound waves in air are characterized as:
Basics of Everyday Science: RAS Prelims MCQs
200 RAS Prelims MCQs on the basics of everyday science test the scientific method, the laws of motion, chemical bonding and the cell theory. The questions use daily-life examples, such as the recoil of a gun and the orbit of a satellite, and the explanations give the principle behind each example so that you can reason out similar questions.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 61–70 of 200 questions
Q62. The pitch of a sound depends primarily on its:
Explanation
The pitch of a sound is the human perception of how "high" or "low" a note sounds. This characteristic is primarily determined by the frequency of the sound wave, which is the number of vibrations per second. Higher frequencies are perceived as higher pitches, while lower frequencies correspond to lower pitches. Amplitude, in contrast, determines the loudness or intensity of the sound.
Q63. Consider the following statements regarding the speed of sound:
I. It is greater in solids than in liquids.
II. It increases with an increase in the temperature of the medium.
III. It can travel through a perfect vacuum.
IV. It is greater in humid air than in dry air.
Which of the above statement(s) is/are correct?
I. It is greater in solids than in liquids.
II. It increases with an increase in the temperature of the medium.
III. It can travel through a perfect vacuum.
IV. It is greater in humid air than in dry air.
Which of the above statement(s) is/are correct?
Explanation
Sound travels fastest in solids due to the close proximity of atoms, and its speed increases with temperature because particles move more quickly. Humid air is less dense than dry air, which actually allows sound to travel faster. Crucially, sound is a mechanical wave and requires a medium to propagate; therefore, it cannot travel through a vacuum, making that statement incorrect.
Q64. To hear a distinct echo, the minimum distance between the listener and the reflecting surface should be approximately:
Explanation
To hear a distinct echo, the human ear requires a time interval of at least zero point one seconds between the original sound and the reflected one. Given the speed of sound in air is approximately three hundred and forty-four meters per second, the sound must travel a total distance of thirty-four point four meters. Thus, the reflecting surface must be half that distance.
Q65. The technique of using high-frequency sound waves to detect objects underwater is called:
Explanation
SONAR, which stands for Sound Navigation and Ranging, is a technique that uses ultrasonic sound waves to detect and locate objects underwater. A transmitter sends out a sound pulse, which reflects off objects and returns to a receiver. By measuring the time delay between the emission and the echo, the distance and position of underwater obstacles can be accurately determined.
Q66. The normal audible frequency range for an average human ear is:
Explanation
The normal audible frequency range for a healthy human ear typically spans from twenty Hertz to twenty thousand Hertz. Frequencies below this range are known as infrasonic, while those above are called ultrasonic. As humans age, the upper limit of this range often decreases, particularly affecting the ability to hear high-pitched sounds, though the lower limit generally remains stable near twenty Hertz.
Q67. The loudness of a sound is directly determined by the wave’s:
Explanation
Loudness is the subjective perception of sound intensity and is directly determined by the amplitude of the sound wave. Amplitude represents the maximum displacement of particles from their rest position. Waves with larger amplitudes carry more energy and are perceived as louder, while smaller amplitudes result in softer sounds. This relationship is often measured on a logarithmic scale using decibels as units.
Q68. Which of the following medical applications utilizes sound waves above the human hearing limit?
Explanation
Ultrasonography is a medical imaging technique that utilizes high-frequency sound waves, well above the human hearing limit of twenty thousand Hertz. These ultrasonic waves are directed into the body and reflect off internal organs and tissues. The returning echoes are captured and processed by a computer to create real-time images, making it a safe and non-invasive tool for diagnostic monitoring.
Q69. Select the correct sequence of media arranged in increasing order of the speed of sound through them:
Explanation
The speed of sound depends on the density and elasticity of the medium. Sound travels slowest in gases like air because the molecules are far apart. In liquids like water, the particles are closer, allowing faster transmission. It travels fastest in rigid solids like steel, where strong molecular bonds and high elasticity facilitate the rapid transfer of vibrational energy between adjacent particles.
Q70. The apparent change in frequency of a sound due to the relative motion between the source and the observer is known as:
Explanation
The Doppler Effect describes the apparent change in the frequency or wavelength of a wave as observed by someone moving relative to the wave source. As a sound source approaches an observer, the waves are compressed, leading to a higher perceived pitch. Conversely, as the source moves away, the waves stretch out, resulting in a lower perceived pitch than the original sound.Answer key for these questions
| Q | Correct answer |
|---|---|
| 61 | (c) Longitudinal mechanical waves |
| 62 | (d) Frequency |
| 63 | (a) I, II and IV |
| 64 | (b) 17.2 meters |
| 65 | (b) SONAR |
| 66 | (b) 20 Hz to 20,000 Hz |
| 67 | (c) Amplitude |
| 68 | (d) Ultrasonography |
| 69 | (a) Air < Water < Steel |
| 70 | (b) The Doppler Effect |
Key facts from Basics of Everyday Science
- Inductive reasoning draws a general conclusion from specific observations; a control variable is kept constant in an experiment; communicating the results is the last step of the scientific method.
- Newton’s second law relates force, mass and acceleration; the recoil of a gun illustrates the third law.
- Momentum is the product of mass and velocity; impulse is equal to the change in momentum.
- A satellite in uniform circular orbit is held by the centripetal force provided by gravity.
- Water (H₂O) and N₂ show covalent bonding; sodium chloride, MgO and CaF₂ are ionic.
- The classical cell theory does not say that all cells have a true nucleus.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Basics of Everyday Science?
This page has 200 practice MCQs on Basics of Everyday Science (Science and Technology). Each has the correct answer, and most have an explanation.
What is the product of mass and velocity called?
Momentum. Newton’s second law says that the rate of change of momentum is equal to the force applied, and impulse is equal to the change in momentum of a body.
Which law explains the recoil of a gun?
Newton’s third law of motion. The gun pushes the bullet forward, and the bullet pushes the gun back with an equal and opposite force, which is felt as recoil.
What holds a satellite in a circular orbit?
The centripetal force provided by gravity. The Earth’s pull keeps changing the direction of the satellite’s velocity so that it moves in a circle and does not fly off in a straight line.