Ek Chammach Se Shuruaat 🥄
Ghar se ek chamakta hua chammach uthao aur dono taraf se apna chehra dekho.
🔹 Andar wali (gehri) taraf se dekho — paas se dekhne par chehra
bada aur seedha dikhega. Ab chammach ko door le jao — achanak chehra
ULTA ho jaayega! Ye concave (avatal) mirror (darpan) hai.
🔹 Bahar wali (ubhri) taraf se dekho — chehra hamesha
chhota aur seedha dikhega, chaahe paas rakho ya door. Ye
convex (uttal) mirror hai.
📌 Spherical mirror (gola darpan) ek gend (sphere) ke kate hue tukde jaisa hota hai.
🔹 Concave — reflection (paraavartan) andar wali (dhansi hui) satah
se. Ye roshni ko ek jagah jodta (converge) hai.
🔹 Convex — reflection bahar wali (ubhri) satah se. Ye
roshni ko faila (diverge) deta hai.
CONCAVE mein "CAVE" (gufa) chhupa hai — gufa andar dhansi hoti hai. Toh concave =
andar dhansa hua.
Aur concave = Converging (jodne wala), convex =
Diverging (failane wala). Dono "C" saath yaad karo.
📍 Chaar Zaroori Bindu Aur Rekhaein
Aage badhne se pehle ye chaar shabd pakke kar lo — poora chapter inhi par chalega.
| Shabd | Matlab |
|---|---|
| Pole (P) | Mirror ki satah ka beech ka bindu. Saari dooriyan yahin se naapi jaati hain. |
| Centre of curvature (C) | Us gend ka kendra jiska ye mirror tukda hai. |
| Radius of curvature (R) | P se C tak ki doori — yani gend ki radius. |
| Principal focus (F) | Wo bindu jahan axis ke parallel aayi rays reflection ke baad milti hain. |
| Focal length (f) | P se F tak ki doori. |
| Principal axis | P aur C se guzarne wali seedhi rekha. |
| Aperture | Mirror ka chaudai (kitna bada tukda hai). |
📌 Sabse zaroori rishta — yaad kar lo:
R = 2f yani
f = R/2
Focus hamesha P aur C ke bilkul beech mein hota hai. Numericals mein aksar R diya
hota hai aur f chahiye hota hai — ya ulta. Ye ek line bahut number bachaayegi.
Convex mirror parallel rays ko faila deta hai — wo kabhi milti nahi! Toh focus
hai kahan?
Un failti hui rays ko peeche ki taraf badhaao — wo mirror ke
PEECHE ek bindu par milti hui lagti hain. Wahi convex mirror ka focus hai.
Isiliye convex mirror ka focus virtual hai aur uska f
positive hota hai (sign convention mein). Concave ka focus
saamne hai, isliye uska f negative.
📐 Ray Diagram Ke 4 Niyam
Image kahan banega — ye pata karne ke liye hume sirf do rays khinchni hoti hain. Par chunne ke liye chaar aasaan niyam hain. Koi bhi do chun lo.
📌 Practical tip: zyadatar sawaalon mein Niyam 1 + Niyam 3 sabse
aasaan hai. Ek ray object ke sire se parallel bhejo (wo F se guzregi), doosri C se bhejo (wo wapas
aayegi). Jahan dono milein — wahin image ka sira hai.
Convex mirror mein bhi wahi chaar niyam lagte hain — bas F aur C mirror ke
peeche hote hain, isliye rays unki taraf badhti hui maani jaati
hain.
🎬 Concave Mirror — Chhe Positions
Concave mirror ka image object ki jagah par nirbhar karta hai. Board exam mein ye table seedha poocha jaata hai — isliye ise samajh kar yaad karo.
| Object kahan | Image kahan | Size | Nature |
|---|---|---|---|
| Anant par (bahut door) | F par | Bahut chhota (bindu jaisa) | Real, inverted |
| C se pare (beyond C) | F aur C ke beech | Chhota | Real, inverted |
| C par | C par | Utna hi bada | Real, inverted |
| C aur F ke beech | C se pare | Bada | Real, inverted |
| F par | Anant par | Bahut bada | Real, inverted |
| F aur P ke beech | Mirror ke peeche | Bada | Virtual, erect |
🎯 Poori table ek line mein: concave mirror ka image
hamesha real aur inverted hota hai — sivaay ek haalat ke: jab
object F aur P ke beech ho. Sirf wahi ek case virtual, erect aur bada deta hai.
Aur yahi wo case hai jo aapne chammach ke paas dekha tha!
Dhyaan do: object aur image aapas mein jagah badal sakte hain!
Object C se pare → image F aur C ke beech.
Object F aur C ke beech → image C se pare.
Yani agar aap object ko image ki jagah rakh dein, toh image object ki jagah ban jaayega. Ise
principle of reversibility kehte hain — roshni ka raasta hamesha
ulta bhi utna hi sahi hota hai.
🔵 Convex Mirror — Hamesha Ek Jaisa
Convex mirror ki kahani bahut chhoti hai — kyunki uska jawab hamesha ek hi hai.
📌 Convex mirror ka image hamesha:
🔹 Virtual (mirror ke peeche)
🔹 Erect (seedha)
🔹 Diminished (chhota)
Object kahin bhi rakho — paas, door, bahut door — jawab
kabhi nahi badalta. Bas image thoda aur chhota hota jaata hai.
Gaadi ke side mirror convex hote hain. Kyun?
✅ Faayda: chhota image banane ka matlab hai ki
bahut zyada ilaaka ek hi chhote mirror mein aa jaata hai — yani
wider field of view. Driver ko peeche ka bahut bada hissa dikh jaata hai.
✅ Image hamesha seedha rehta hai — ulta hota toh driver confuse ho jaata.
⚠️ Nuksaan: cheezein choti dikhti hain, isliye door lagti hain.
Isi wajah se un mirror par likha hota hai:
"Objects in mirror are closer than they appear".
| Kahan use hota hai | Kaunsa mirror | Kyun |
|---|---|---|
| Gaadi ka side mirror | Convex | Wider view + seedha image |
| Dukaan ki nazar rakhne wala mirror | Convex | Poori dukaan ek mirror mein |
| Daadhi banane ka mirror | Concave | Paas se bada aur seedha chehra |
| Dentist ka mirror | Concave | Daant ka bada image |
| Torch aur gaadi ki headlight | Concave | Bulb F par → parallel roshni door tak |
| Solar cooker | Concave | Sooraj ki rays ek bindu par jodta hai |
| Telescope ka bada mirror | Concave | Door ke taaron ki roshni jodta hai |
Rajasthan ke gaon-dehat mein concave solar cooker aur bade
solar concentrator aam ho gaye hain. Mount Abu ke paas
Brahma Kumaris ka "India One" solar plant duniya ke sabse bade solar steam
system mein se ek hai — hazaron logon ka khaana bina gas aur lakdi ke banta hai.
Kaam kaise karta hai? Bade concave mirror sooraj ki parallel rays ko ek
focus par jodte hain — wahan taapmaan itna badh jaata hai ki paani se
bhaap (steam) ban jaati hai.
Yahi soch Ladakh mein bhi kaam aati hai, jahan lakdi milna mushkil hai par dhoop
saal bhar tez rehti hai. Ek chapter ka R = 2f, aur usse crore rupaye ka eendhan aur hazaron ped
bach jaate hain.
🧠 Apne Aap Ko Test Karo
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