Relate loudness to amplitude
Scenario
Agar aap TV ka volume badhate hain, toh uske andar aawaz patli ya bhaari nahi hoti, balki aur zyada zor ki ho jati hai.
Sound ki is 'loudness' ke peechhe konsi physical property chhipi hai?
Mental model
Zor se dhakka = zyada amplitude = zyada loud sound.
Jaise jhoole ko zor se push karne par wo lamba distance cover karta hai (bada amplitude), waise hi jab source zor se vibrate karta hai, toh uski wave ka amplitude badh jata hai aur sound loud sunai deti hai.
Explanation
Loudness is baat ka measure hai ki sound ka energy level hamare kaano par kitna strong impact dalta hai. Physics mein, loudness seedhe tor par **amplitude** par depend karti hai.
Amplitude ka matlab hai ki vibration ke dauran particles apni original position se maximum kitna door tak move karte hain. Agar ek drum ko halke se bajaya jaye, toh uska surface thoda sa hi vibrate karega. Iska amplitude chhota hoga aur sound soft sunai degi.
Lekin agar aap us drum par zor se maarte hain, toh surface ki movement bahut badi hogi, yaani amplitude badh jayega. Is badhe hue amplitude ki wajah se jo sound wave banegi usme zyada energy hogi, aur woh hamein loud sunai degi. Infact, loudness amplitude ke square ke proportional hoti hai, toh thoda sa amplitude badhne par bhi loudness kafi badh jati hai.
Isliye, jab bhi hamein kisi aawaz ko loud karna hota hai, toh hum actually us sound wave ka amplitude increase kar rahe hote hain.
Worked example
Problem: You have two speakers playing the same song. One is set at a low volume and the other at a high volume. Which speaker produces sound waves with a greater amplitude?
- Loudness seedhe amplitude par depend karti hai.
- Kyunki dusra speaker high volume par hai (zyada loud), uski wave ka amplitude bhi zyada bada hoga.
Answer: The speaker at a high volume produces sound waves with a greater amplitude.
Problem: A guitar string is plucked softly, and then plucked strongly. How does the sound change in terms of pitch and loudness?
- Jab hum zor se pluck karte hain, toh string apni mean position se zyada door jaati hai, yaani amplitude badhta hai.
- Amplitude badhne par loudness badhti hai, lekin uski frequency (pitch) same rehti hai.
Answer: The sound becomes louder, but the pitch remains the same.
Key points
- Amplitude: The maximum displacement of the particles from their mean position.
- Loudness: Loudness depends mainly on the amplitude of the sound wave. Greater amplitude means louder sound.
Common mistakes
- Confusing loudness and pitch: Amplitude se loudness (volume) control hoti hai aur frequency se pitch (shrillness). Ek patli aawaz dheemi ho sakti hai aur moti aawaz tez, isliye dono ko confuse mat karo.
Recall questions
- What determines the loudness of a sound?
- If the amplitude of a sound wave is increased, what happens to its loudness?
- What property of a wave determines its loudness?
Questions & answers
Why is the sound of a baby shriller than that of an adult, but often not as loud?
The baby's vocal cords produce high frequency (higher pitch), making it shriller. But because the vocal cords vibrate with less amplitude, the sound might not be as loud.
Approach: Distinguish between frequency (pitch) and amplitude (loudness).
If you hit a drum harder, what happens to its amplitude and loudness?
The amplitude of the vibration increases, which makes the sound louder.
Approach: Relate the force of the strike to amplitude and then to loudness.