1.6.14 · D1 · Physics › Oscillations & Waves › Wave parameters — amplitude, wavelength, frequency, period,
Ek wave ek aisi wiggle hai jo space mein repeat hoti hai (tum dekh sakte ho ki ek hi shape har itne metres mein milti hai) aur time mein bhi (ek jagah ek steady beat par hiltii rehti hai). Parent page par jo bhi symbol hai, woh bas usi repeat ka naam hai — kitni badi hai, kitni lambi hai, kitni baar hoti hai, ya kitni tezi se chalti hai.
Pehle v = f λ padhne se pehle — aur sach mein samajhne se pehle — tumhe ye jaanna chahiye ki har squiggle ka matlab kya hai aur — aur isse bhi zaroori — ek real wave par woh kaisa dikhta hai . Yeh page har symbol ko bilkul zero se banata hai. Hum dheere chalenge, ek picture at a time. Yahan kuch bhi assume nahi kiya gaya; jo bhi parent note mein use hua hai, usse hum neeche define karenge.
Waves ke baare mein sabse mushkil baat yeh hai ki ek hi picture ke peeche do alag graphs hote hain, aur beginners unhe mix kar dete hain. Aao inhe abhi se saaf alag kar lete hain.
Definition Wave ko dekhne ke do tarike
Ek snapshot time ko rok deta hai aur medium ke saath dekhta hai: horizontal axis position x (metres) hoti hai. Yeh wahi hai jo ek rope ki photograph mein dikhta hai.
Ek ek particle ki movie EK jagah chunti hai aur usse time ke saath dekhti hai: horizontal axis time t (seconds) hoti hai. Yeh wahi hai jo paani par ek cork trace karta hai.
Dono paper par bilkul ek jaise dikh sakte hain — ek wavy curve — lekin horizontal axis ka matlab bilkul alag hota hai. Wavelength snapshot par hoti hai; period movie par hoti hai.
Yeh split apne dimaag mein rakho. Aadha wave confusion to bas yahi hai ki koi "space" ki length ko "time" graph se padh leta hai ya ulta.
y
y itna hai ki ek particle apni rest position se abhi kitna door hai , abhi ke waqt measure kiya gaya. Upar positive y hai, neeche negative y . Units: metres.
Picture: snapshot mein, curve ki height beech ki flat line ke upar y hoti hai. Jab ek particle exactly beech ki line par hota hai, y = 0 hota hai — uska displacement zero hai, chahe woh tezi se move kar raha ho.
y kyun chahiye
Baaki sab cheezein isi ke relative measure hoti hain. "Amplitude" woh sabse bada value hai jo y le sakta hai; "equilibrium" woh jagah hai jahan y = 0 hota hai. y ke bina describe karne ke liye koi wiggle hi nahi hai.
Equilibrium line woh flat level hai jis par medium tab rest karta hai jab koi wave nahi hoti — calm-water level, slack rope. Har graph par yeh woh horizontal centre line hai jahan y = 0 hota hai.
Picture: neeche wali figure mein dashed beech wali line. Crests uske upar niklte hain; troughs uske neeche dip karte hain.
Common mistake "Wave ka bottom zero hai."
Kyun sahi lagta hai: trough sabse neeche wala point hai jo dikhayi deta hai, toh woh floor jaisa lagta hai.
Fix: zero beech mein hai, neeche nahi. Trough y = − A par hota hai (zero se utna hi neeche jitna crest upar hota hai). Yahi woh galti ki jad hai jo parent note mein classic amplitude error ke baare mein batata hai.
Definition Crest, trough, amplitude
Crest wave ka sabse ucha point hai (maximum y ).
Trough sabse neecha point hai (minimum y ).
Amplitude A woh doori hai jo equilibrium line se crest tak hai (equivalently, trough tak ). Units: metres.
Picture: figure mein, beech ki line se crest ki tip tak ka magenta arrow A hai. Trough se crest tak ka pura violet arrow peak-to-peak hai, jo 2 A ke barabar hai — amplitude ka do guna.
Intuition "Beech se" kyun, naa ki "top to bottom"
Ek particle equilibrium ke baare mein symmetrically oscillate karta hai: woh utna hi upar jaata hai jitna neeche. Us motion ka natural size ek taraf ka swing hai, A — woh number hi physics mein aata hai (wave ki energy ∝ A 2 , for instance). Peak-to-peak trip ko double-count karta hai.
λ
λ (Greek letter "lambda") woh medium ke saath sabse kam doori hai jiske baad shape repeat hoti hai . Crest se agle crest tak, ya trough se agle trough tak. Units: metres. Yeh ek snapshot quantity hai.
Picture: snapshot (position axis) par, λ do neighbouring crests ke beech ka horizontal gap hai — figure mein orange bracket. Itna door chalo aur wave "phir se same dikhti hai."
sabse chhota repeat measure karte hain
Shape 2 λ , 3 λ , aur isse aage bhi repeat hoti hai — lekin woh sirf multiples hain. Wavelength woh fundamental repeat distance hai, sabse chhoti brick jisse poora pattern tila gaya hai.
T
T woh time hai jisme ek single particle ka ek full up-and-down cycle pura hota hai . Units: seconds. Yeh ek movie quantity hai — isse dekhne ke liye ek jagah ko time ke saath watch karna padta hai.
Picture: movie graph (time axis) par, T woh horizontal gap hai do un moments ke beech jab particle phir se usi height par ho aur usi direction mein move kar raha ho. Yeh wavelength ka time-axis twin hai.
T aur λ cousins kyun hain, same kyun nahi
Dono ka matlab "ek full repeat" hai, isliye beginners inhe fuse kar dete hain. Lekin λ space mein repeat hai (metres) aur T time mein repeat hai (seconds). Bilkul alag dimensions. Yeh dono sirf wave ki speed ke zariye milte hain, jo hum D-later pages mein banate hain: λ = v T .
f
f woh number hai jitne complete cycles ek particle har second mein complete karta hai . Units: hertz, jahan 1 Hz = 1 s − 1 ("one per second").
f = 1/ T kyun — tool bas division hai
Maano ek cycle T = 0.25 s leti hai. Poore second mein kitne fit hote hain? Tum divide karte ho: 1 ÷ 0.25 = 4 cycles. Yahi literally "per second" ka matlab hai — total time divided by time-per-one. Toh f = 1/ T . Koi calculus nahi, koi trick nahi: yeh "kitne fit hote hain" ki definition hai.
v
v woh speed hai jis par fixed phase ka ek feature (jaise, ek particular crest) medium se guzarta hai. Units: metres per second, m/s . Speed ka matlab hamesha distance ÷ time hota hai.
Picture: do snapshots compare karo jo thodi si alag time par li gayi hain — poora pattern sideways khisakal gaya hai. Ek crest track karo; woh kitna move hua divided by kitna time laga woh v hai.
v iska matlab yeh nahi ki tum kitni zyada shake karte ho
Ek crest ek shape hai, aur shapes medium se ek speed par ride karti hain jo medium decide karta hai (rope ki tension aur weight, air ki stiffness). Zyada tezi se shake karne se zyada crests ban jaate hain, zyada paas pack hue — iska matlab yeh nahi ki har ek zyada tezi se travel karta hai. Isliye baad mein f aur λ trade off karte hain jabki v stable rehta hai.
Definition Symbols ko zor se padhna
λ — "lambda", ek Greek L, length in space (wavelength) ke liye use hota hai.
T — capital tee, period (ek time). Yahan temperature nahi!
f — frequency .
Hz — hertz , frequency ki unit, = s − 1 .
s − 1 — "per second"; chhota − 1 exponent ka matlab hai "one divided by," toh s − 1 = 1/ s .
≡ — "is defined as" ("equals" se zyada strong: yeh meaning set karta hai).
∝ — "is proportional to" (ek constant factor tak lockstep mein badhta hai).
− 1 exponent trick kyun matter karti hai
s − 1 likhne se "per second" ki jagah units fractions ki tarah cancel hote hain. v = f λ mein: [ s − 1 ] × [ m ] = m/s — seconds aur "per second" cancel hokar speed de dete hain. Notation tumhare liye bookkeeping karta hai .
Displacement y and equilibrium y=0
Wavelength lambda in space
Wave equation v = f lambda
Top-down padho: displacement aur equilibrium amplitude define karte hain; space-repeat se wavelength milti hai, time-repeat se period milti hai; period flip hokar frequency ban jaata hai; wavelength aur period milkar speed set karte hain; aur frequency times wavelength tumhe woh master equation deta hai jis par pura topic built hai.
Right-hand side cover karo aur dekho ki reveal karne se pehle answer de sako ya nahi.
y displacement kya hai?Ek particle abhi apni rest position se kitna door hai, metres mein (upar positive, neeche negative).
Wave par y = 0 kahan hai? Equilibrium line par — flat beech mein, trough mein nahi.
Amplitude A ko ek line mein define karo. Equilibrium line se crest tak ki doori; peak-to-peak swing ka aadha.
A ke terms mein peak-to-peak swing?2 A .
Wavelength λ kya hai, aur yeh space ya time quantity hai? Sabse kam doori jis par shape repeat hoti hai (crest to crest); metres mein ek space quantity.
Period T kya hai, aur yeh space ya time hai? Ek particle ka ek full cycle ka time; seconds mein ek time quantity.
f = 1/ T kyun hai?"Cycles per second" total time (1 s) divided by time-for-one-cycle (T ) hai, jo 1/ T hai.
1 Hz ka matlab kya hai?Ek complete cycle per second, yani s − 1 .
Wave speed v kya set karta hai? Medium ki properties, naa ki tum kitni tezi se shake karte ho.
s − 1 ka matlab kya hai aur aise kyun likhte hain?"Per second"; − 1 exponent se v = f λ mein units cleanly cancel hote hain.
Simple Harmonic Motion — yahan har particle ki up-and-down motion hi SHM hai; A aur T seedha usi se aate hain.
Transverse and Longitudinal Waves — yahi symbols dono wave types describe karte hain.
The Wave Equation y(x,t) — in sab symbols ko y = A sin ( k x − ω t ) mein assemble karta hai.
Speed of Waves on a String — explain karta hai ki v medium-set kyun hota hai.