Physics ยท Science General

Acoustics and Sound Waves

2,160 Questions

Acoustics and sound waves deal with mechanical vibrations traveling through media like air and water. Key concepts include wave reflection, beats, echoes, the Mach number, and infrasound. These physics fundamentals are regularly tested in general science sections of multiple competitive exams.

Sound wave propagationEchoes and reflectionWave interferenceMach numberInfrasound frequency

Acoustics and Sound Waves Questions

Multiple choice softskills creativity

What is the Expansion for ZEN? (Maruthi ZEN)

  1. Zero Emmision Noise

  2. Zero Effective Noise

  3. Zero Engine Noise

  4. Zero Effusion Noise
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Maruti Zen, a popular car in India, was marketed as 'Zero Engine Noise' to emphasize its quiet operation. The other options are made-up expansions that don't match the actual branding.

Multiple choice technology

High Frequency (HF) RFID tags use

  1. 125 kHz

  2. 915 MHz

  3. 2.54 GHz

  4. 13.56 MHz
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

High Frequency (HF) RFID operates at 13.56 MHz, which is the international standard for HF RFID systems (ISO/IEC 14443, ISO/IEC 15693). Low Frequency (LF) uses 125 kHz, Ultra High Frequency (UHF) uses 915 MHz, and microwave uses 2.54 GHz.

Multiple choice technology

Blue tooth changes the frequency

  1. 79 times per minute

  2. 1600 times per minute

  3. 79 times per second

  4. 1600 times per second
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bluetooth uses frequency-hopping spread spectrum (FHSS) to minimize interference. It hops 1600 times per second across 79 channels in the 2.4 GHz ISM band. This rapid hopping makes the connection robust against interference. Option C (79 per second) confuses the number of channels with hop rate, while A and B use minutes instead of seconds.

Multiple choice technology

Blue tooth devices communicates using

  1. Radio waves

  2. Infra red

  3. UV rays

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bluetooth operates in the 2.4 GHz ISM band using radio waves. It does not use infrared (line-of-sight limitation) or UV rays (harmful, not used for short-range communication). Radio waves allow non-line-of-sight communication through walls and obstacles within the 10-100 meter range.

Multiple choice technology

Blue tooth operates at

  1. 2.45 GHz

  2. 2.45 MHz

  3. 2.45 BHz

  4. 2.4 Hz
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bluetooth operates in the 2.4-2.48 GHz ISM (Industrial, Scientific, Medical) band. 2.45 GHz is the center frequency commonly cited. Options in MHz (megahertz) would be 1000x too small. BHz is not a standard unit. Hz alone is far too low. This is the same band used by WiFi and microwaves.

Multiple choice technology

DTMF

  1. Dual Tone Multi-Frequency

  2. Durable Tone Multi-Frequency

  3. Distance Travelled Multiple Frequency

  4. Digital TMF
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DTMF stands for Dual Tone Multi-Frequency, the signaling system used in telephones where each key press generates two specific tones simultaneously. This enables reliable digit recognition over telephone networks.

Multiple choice technology web technology

The frame rate is:

  1. FPS (Frame Per Second)

  2. FPM (Frame Per Minute)

  3. FPS (Frame Per Scene)

  4. FPS (Frame Per Shockwave)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Frame rate in Flash and multimedia is measured in FPS (Frames Per Second), which determines how many individual frames are displayed each second. This standard measurement applies across video, animation, and interactive media. Options B, C, and D are incorrect - FPM, 'per scene', and 'per shockwave' are not standard frame rate units.

Multiple choice technology

The sampling rate, (how many samples per second are stored) for a CD is...?

  1. 48.4 kHz

  2. 22,050 Hz

  3. 44.1 kHz

  4. 48 kHz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

CDs use a standardized sampling rate of 44.1 kHz (44,100 samples per second), which was chosen to balance audio quality with storage capacity. This rate is sufficient to capture frequencies up to 22.05 kHz, covering the full range of human hearing (20 Hz to 20 kHz). Options A and D are close but incorrect - 48 kHz is used in professional audio, and 48.4 kHz is not a standard rate. Option B at 22,050 Hz is exactly half the correct rate.

Multiple choice technology

The sampling rate, (how many samples per second are stored) for a CD is...?

  1. 48.4 kHz

  2. 22,050 Hz

  3. 44.1 kHz

  4. 48 kHz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The standard sampling rate for audio CDs is 44.1 kHz (44,100 samples per second). This rate was chosen because it can accurately capture frequencies up to 20 kHz, which covers the full range of human hearing (20 Hz to 20 kHz), following the Nyquist theorem which states the sampling rate must be at least double the highest frequency.

Multiple choice technology

What frequency range is the High Frequency band?

  1. 100 kHz

  2. 1 GHz

  3. 30 to 300 MHz

  4. 3 to 30 MHz
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

High Frequency (HF) band is the ITU designation for 3 to 30 MHz radio frequencies. This band is used for shortwave radio broadcasting, amateur radio, and various communications services. The other options are incorrect: 100 kHz would be in the LF band, 1 GHz is in the UHF band, and 30-300 MHz is the VHF band.