The number of oscillations or vibrations per second is called the ______?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

Frequency is the physical quantity that measures the number of complete oscillations or vibrations that occur in one second.
The standard unit for frequency is Hertz (Hz), where 1 Hz equals one cycle per second.
This term precisely matches the definition provided in the question stem.
In the context of sound, frequency is the primary determinant of perceived pitch.

Option A: Wavelength measures the spatial distance of a single wave cycle (e.g., from crest to crest), not the number of cycles per unit of time.
Option C: Shrillness is the subjective perception of a sound's pitch. While it is determined by frequency, it is a psychoacoustic quality, not the objective physical measurement itself.
Option D: Amplitude is the measure of a wave's maximum displacement from its equilibrium position. It relates to the wave's intensity or energy (e.g., loudness of a sound), not its rate of oscillation.

Visual 1: Diagram - An annotated diagram of a sine wave, clearly labeling the Wavelength (distance between two crests), Amplitude (height from the central axis to a crest), a Crest, and a Trough. This helps visually differentiate the key properties of a wave.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition of Frequency in Wave Mechanics as background academic context rather than a clinical decision trigger.
Understanding frequency is crucial in many medical applications. For example, ultrasound imaging uses very high-frequency sound waves (in the megahertz range) to create images of internal body structures.
In cardiology, the frequency of heartbeats is measured as the heart rate in beats per minute. Analyzing the frequency components of an ECG can help diagnose various arrhythmias.
What if? If the question asked for the 'time taken to complete one oscillation,' the correct answer would be the 'Time Period (T),' which is the reciprocal of frequency (T = 1/f).

How to Approach the Question

First, identify the key phrase in the question: 'number of oscillations or vibrations per second'. This is a request for a specific definition.
This is a factual recall question. You need to access your knowledge of basic physics and wave properties.
Systematically evaluate each option against the definition.
Recall that 'Frequency' is defined as cycles per unit time (seconds). This directly matches the question.
Eliminate 'Wavelength' as it is a measure of distance.
Eliminate 'Amplitude' as it is a measure of displacement or intensity.

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Attempt every question from this paper in a timed mock, then review the full solution for each one.