Spherical Mirrors Kya Hain? (Concave aur Convex Mirror)
Chammach mein aapka chehra ulta kyun dikhta hai? 🥄
🧭 Is Post Mein
📖 Kahani: Golu ki Jaadui Chammach
Raat ke khaane ka time tha. Golu dal-chawal khaate-khaate apni steel ki chammach ko ghoor raha tha. Achanak woh chillaya: “Mummy! Chammach mein mera chehra ulta ho gaya hai! Sir neeche, thodi upar!”
Uski behen Priya ne chammach palat kar dekhi. “Is taraf toh tera chehra seedha hai, bas chhota sa, jaise kisi ne door se photo kheenchi ho.”
Rohan bhaiya hans kar bole: “Aur bathroom ke sheeshe mein toh tu bilkul utna hi bada aur seedha dikhta hai. Ek hi chamakti cheez, teen alag chehre!”
Golu soch mein pad gaya: Chammach ke andar ulta, bahar chhota aur seedha, aur sheeshe mein bilkul barabar. Aisa kyun? Iska raaz chhupa hai sheeshe ke aakaar (shape) mein. Chaliye, aaj yahi raaz kholte hain. 🔍
🎯 Is Post Mein Kya Seekhenge
- Plane mirror aur curved (mude hue) mirror mein fark
- Spherical mirror kise kehte hain, aur iska naam “spherical” kyun hai
- Concave mirror aur convex mirror: pehchaan aur diagram mein kaise banate hain
- Spherical mirror asal mein kaise banaye jaate hain (coating ka khel)
- Chammach aur steel ki katori se ghar pe mirror ka experiment
🧱 Basics: Pehle Yeh Aana Chahiye
1. Reflection (paravartan): jab roshni kisi chamakdaar, chikni sateh se takra kar wapas laut aati hai. Isi se humein sheeshe mein apna image (pratibimb) dikhta hai.
2. Plane mirror (samtal darpan): bilkul seedha, sapaat sheesha, jaise ghar ka dressing table ka sheesha. Isme image seedha (erect) aur object jitna hi bada banta hai.
3. Lateral inversion: sheeshe mein daayaan haath baayaan dikhta hai. Yeh Class 7 mein padha tha.
4. Sphere (gola): football ya gend jaisa poora gol aakaar. Ek hollow sphere andar se khaali gola hota hai, jaise plastic ki khaali gend.
💡 Concept: Spherical Mirror Kya Hai?
Step 1: Har mirror sapaat nahi hota. Ghar ka sheesha sapaat (flat) hai, isliye use plane mirror kehte hain. Lekin chammach, steel ki katori, karchhi (ladle), ya gaadi ka side wala sheesha, inki chamakti sateh mudi hui (curved) hai. Yeh sab bhi mirror ki tarah kaam karte hain, par inme image alag dikhta hai.
Step 2: Spherical mirror ki paribhasha. Jis mirror ki chamakdaar (reflecting) sateh ek khokhle gole (hollow sphere) ke tukde jaisi mudi ho, use spherical mirror (golakaar darpan) kehte hain.
Step 3: Ek tukde ki do sateh. Us mude hue tukde ki do taraf hoti hain:
Yaad rakhne ki trick: conCAVE = cave yaani gufa. Gufa andar ki taraf jaati hai!
Trick: convex mein “bahar ubhaar”, jaise gubbare ka bahar ka hissa.
Step 4: Chammach = do mirror ek saath! Steel ki chammach ka andar wala hissa (jisme dal aati hai) concave mirror ki tarah kaam karta hai. Uska pichhla, ubhra hua hissa convex mirror ki tarah. Isliye Golu ko ek taraf ulta chehra aur doosri taraf chhota seedha chehra dikha.
Step 5: Diagram mein kaise banate hain? Book aur exam mein spherical mirror ko ek mudi hui line (arc) se dikhate hain. Jo taraf chamakti nahi (peeche ki taraf), use chhoti tirchhi lakeeron se shade kar dete hain. Yaani:
🔹 Convex: ubhri taraf chamakdaar, khokhli (peeche ki) taraf shaded.
🔹 Plane: seedhi line, peeche ki taraf shaded.
Step 6: Pehchaanein kaise? Teen aasan tareeke:
2. Image dekho: plane mirror mein image hamesha barabar aur seedha. Convex mein hamesha chhota aur seedha. Concave mein paas se bada aur seedha, aur door jaane par ulta. (Yeh Post 2 mein detail mein.)
3. Haath se mehsoos karo (sirf chammach/katori jaisi cheezon pe, asli sheeshe pe ungli ke nishaan padte hain).
Ek line mein: Spherical mirror = khokhle gole ka chamakdaar tukda; andar chamke toh concave, bahar chamke toh convex.
🖼️ Diagrams: Picture se Samjho
🔐 Deep Concept: Ek Sheesha, Do Roop, aur “Kitna Muda” ka Khel
Raaz 1: Mirror gend kaat kar nahi banta. Spherical mirror ko hum “khokhle gole ka tukda” sirf samajhne ke liye kehte hain. Asal mein factory mein kaanch ke ek sapaat tukde ko ghis-ghis kar aur polish karke mudi hui shape di jaati hai. Phir uski ek taraf chamakdaar dhaatu (jaise aluminium) ki patli parat chadha di jaati hai.
🔸 Parat andar wali khokhli sateh pe chadhi → roshni bahar ki ubhri taraf se lautegi → convex mirror.
Yaani ek hi mude hue kaanch se, parat kis taraf lagi hai, bas usi se tay hota hai ki woh concave banega ya convex! Jis taraf parat lagi, woh mirror ki peeth ban jaati hai.
Raaz 2: Bahut bada gola = lagbhag sapaat. Ek chhoti gend ka tukda bahut muda hota hai. Lekin socho, hamari Dharti bhi ek gola hai, phir bhi khet aur maidaan humein sapaat lagte hain, kyunki gola bahut bada hai. Isi tarah, jitne bade gole ka tukda, mirror utna kam muda hoga aur plane mirror jaisa bartaav karega. Aur jitna chhota gola (jaise chammach), mirror utna zyada muda aur image mein utna zyada badlaav. Is tarah plane mirror ko ek “bahut-bahut bade gole ka tukda” bhi samajh sakte hain.
✏️ Examples: Kaun sa Mirror Hai?
Chamakti sateh andar dhansi hai, jisme dal aati hai.
Katori ulti rakho toh chamakti sateh bahar ubhri hui hai. Isme chehra chhota aur seedha dikhta hai.
Peeche ki gaadiyan chhoti aur seedhi dikhti hain, aur zyada sadak nazar aati hai. (Iske upyog Post 3 mein.)
Andar se khokhli aur chamakdaar, taaki bulb ki roshni aage ek taraf bheje.
Sateh bilkul sapaat hai, isliye image barabar aur seedha.
Daant ke paas rakhne pe daant bade dikhte hain, aisa concave mirror paas se karta hai.
⚖️ Difference Table: Plane vs Concave vs Convex
| Baat | Plane mirror | Concave mirror | Convex mirror |
|---|---|---|---|
| Sateh | Sapaat (flat) | Andar ki taraf dhansi | Bahar ki taraf ubhri |
| Chammach mein | (koi nahi) | Andar wala hissa | Peeth wala hissa |
| Image ka size | Hamesha barabar | Paas se bada, door se badalta | Hamesha chhota |
| Seedha ya ulta | Hamesha seedha | Paas se seedha, door se ulta | Hamesha seedha |
| Hindi naam | Samtal darpan | Avtal darpan | Uttal darpan |
| Example | Dressing table | Torch reflector, dentist mirror | Gaadi ka side mirror |
🚫 Misconceptions: Log aisa sochte hain… lekin
❌ “Concave mirror hamesha ulta image banata hai.”
✅ Sach: bahut paas rakhi cheez ka image seedha aur bada banta hai. Ulta tab hota hai jab cheez thoda door ho.
❌ “Spherical mirror poora gol (gend jaisa) hota hai.”
✅ Sach: woh gole ka sirf ek chhota tukda jaisa hota hai, poora gola nahi.
❌ “Spherical mirror kaanch ki gend kaat kar banta hai.”
✅ Sach: sapaat kaanch ko ghis kar aur polish karke mod diya jaata hai, phir ek taraf chamakdaar parat lagti hai.
❌ “Sirf kaanch hi mirror ban sakta hai.”
✅ Sach: koi bhi chikni, chamakdaar sateh mirror ki tarah kaam karti hai: steel ki chammach, katori, ya shaant paani bhi.
❌ “Convex mirror mein cheezein gaayab ho jaati hain kyunki chhoti dikhti hain.”
✅ Sach: image chhota hota hai, par cheez wahi rehti hai. Ulta, convex mirror mein ek saath zyada area dikhta hai.
🔤 Key Terms (Exam mein English shabd hi likhna)
❓ FAQs
1. Concave aur convex yaad kaise rakhein?
Con-CAVE = cave (gufa): gufa andar jaati hai, toh concave ki chamakdaar sateh andar dhansi hoti hai. Convex ulta, bahar ubhra hua.
2. Chammach mein kabhi-kabhi andar ki taraf bhi seedha image dikhta hai. Kyun?
Jab chammach ko aankh ke bilkul paas laate ho, toh concave sateh mein image seedha aur bada ho jaata hai. Thoda door karte hi ulta ho jaata hai. Concave mirror mein image object ki doori pe nirbhar karta hai.
3. Diagram mein shading kis taraf karte hain?
Hamesha peeche ki, na chamakne wali taraf. Concave mein ubhri peeth shade hoti hai, convex mein khokhli peeth.
4. Kya spherical mirror mein bhi lateral inversion hota hai?
Haan. Plane, concave aur convex, teeno mirrors mein daayaan-baayaan ulta dikhta hai.
5. Steel ka gol glass bhi mirror hai kya?
Uski bahar ki sateh chamakdaar aur mudi hai, toh image chhota aur kheencha hua dikhega. Lekin glass sirf ek disha mein muda hai (pipe jaisa), gole jaisa nahi. Isliye woh spherical mirror nahi hai. Katori aur chammach spherical ke zyada kareeb hain.
🧪 Activity (NCERT): Chammach ka Sheesha aur Side se Pehchaan
Part A, Saamaan: ek saaf, chamakdaar steel ki badi chammach (tablespoon).
Part B, Saamaan: ek concave aur ek convex mirror (school lab se), ya ek steel ki katori.
Kya dikhega: chammach ke andar wale hisse mein (haath bhar door se) chehra ulta dikhega. Peeth wale hisse mein chehra seedha par chhota dikhega, aur door le jaane pe thoda aur chhota. Dono hi plane mirror se alag hain.
Nishkarsh: chamakdaar mudi sateh bhi mirror ka kaam karti hai. Andar dhansi (concave) aur bahar ubhri (convex) sateh alag-alag image banati hain, aur side se dekh kar inhe aasani se pehchaan sakte hain.
Yeh activity NCERT ki Class 8 Science book Curiosity (Chapter 10) par aadharit hai, aur yahan apne shabdon mein samjhayi gayi hai.
🏠 Mini Experiments (Ghar pe)
Isse kya pata chala? Ek hi bartan ki do sateh do alag tarah ke mirror hain.
Karchhi ki ubhri peeth (convex) mein dekho: poora kamra, darwaza, khidki, sab ek chhote se image mein aa jaata hai. Plane mirror mein itna bada area ek saath nahi dikhta. Yahi convex mirror ka “wide view” hai.
Ghar mein 5 chamakdaar cheezein dhoondho (chammach, katori, thaali, steel ka glass, sheesha). Har ek ke aage likho: plane, concave, convex, ya “sirf ek disha mein muda”. Ghar walon ke saath quiz khelo!
🧠 Think Like a Scientist
Sawaal: Priya ke paas ek chamakdaar gol plate hai jo dekhne mein lagbhag sapaat lagti hai. Woh kaise pata kare ki yeh plane hai, concave hai ya convex?
Scientist ka tareeka dekho
1. Observe (dekho): plate chamakdaar hai, par aankh se pata nahi chalta ki thodi mudi hai ya nahi.
2. Guess (anumaan): agar mudi hogi toh image ka size badlega, kyunki mude mirror image badalte hain.
3. Test (jaanch): (a) plate ko mez pe rakh kar side se dekho. (b) Ek pencil ko plate ke saamne paas se door le jao aur image dekho. (c) Plate pe ek seedha scale rakho: beech mein gap ya jhoolna dikhe toh sateh mudi hai.
4. Result: maan lo pencil ka image paas se bada aur seedha, aur door jaane pe ulta ho gaya.
5. Conclusion: plate concave mirror ki tarah kaam kar rahi hai. Agar image hamesha chhota-seedha hota toh convex, aur hamesha barabar hota toh plane. 🔬
🌍 Real Life Mein Spherical Mirrors
- 🔦 Torch aur headlight: bulb ke peeche concave reflector roshni ko aage ek taraf bhejta hai.
- 🦷 Dentist ka mirror: chhota concave mirror daant ko bada karke dikhata hai.
- 🛵 Gaadi ke side mirror: convex mirror, taaki peeche ka zyada traffic dikhe.
- ⛰️ Pahaadi mod pe sadak ke sheeshe: convex mirror, taaki mod ke doosri taraf ki gaadi dikh jaaye.
- 🏬 Badi dukaanon ke kone mein gol sheesha: convex mirror se ek saath poori dukaan nazar aati hai.
- 🔭 Bade telescope: inme ek bada concave mirror aasmaan ki roshni ikattha karta hai.
🔁 Recap: Poora Post Ek Nazar Mein
- Plane mirror: sapaat; image hamesha seedha aur barabar.
- Spherical mirror: chamakdaar sateh ek khokhle gole ke tukde jaisi mudi hui.
- Concave: chamakdaar sateh andar dhansi (chammach ka andar). Convex: chamakdaar sateh bahar ubhri (chammach ki peeth).
- Chammach ke andar (thoda door se) image ulta; peeth mein seedha aur chhota.
- Diagram mein mirror ki peeth shade karte hain.
- Mirror kaanch ko ghis kar mod ke banate hain; parat bahar lage toh concave, andar lage toh convex.
- Pehchaan: side se dekho, ya image ka size-direction dekho.
✍️ Fill in the Blanks
- Jis mirror ki chamakdaar sateh khokhle gole ke tukde jaisi ho, use ______ mirror kehte hain.
- Jis spherical mirror ki chamakdaar sateh andar ki taraf dhansi ho, woh ______ mirror hai.
- Chammach ki ubhri peeth ______ mirror ki tarah kaam karti hai.
- Plane mirror mein image hamesha object ke ______ size ka hota hai.
- Diagram mein mirror ki na chamakne wali taraf ko ______ kiya jaata hai.
- Agar mude kaanch ki andar wali sateh pe chamakdaar parat lagayi jaaye, toh ______ mirror banega.
Answers
1) spherical · 2) concave · 3) convex · 4) barabar (same) · 5) shade · 6) convex
✅ True / False
- Steel ki chammach ka andar wala hissa concave mirror jaisa hai.
- Convex mirror mein image hamesha ulta banta hai.
- Spherical mirror kaanch ki khokhli gend ko kaat kar banaya jaata hai.
- Plane mirror mein bhi lateral inversion hota hai.
- Gaadi ka side mirror concave hota hai.
- Side se dekh kar concave aur convex mirror pehchaane ja sakte hain.
Answers (kyun ke saath)
1) True: andar ka hissa khokhla aur chamakdaar hai.
2) False: convex mirror mein image hamesha seedha aur chhota hota hai.
3) False: sapaat kaanch ko ghis aur polish karke moda jaata hai, phir parat lagti hai.
4) True: teeno tarah ke mirrors mein daayaan-baayaan ulta dikhta hai.
5) False: side mirror convex hota hai, taaki zyada area dikhe.
6) True: concave ki sateh beech mein dhansi, convex ki ubhri dikhti hai.
🔘 MCQs
Q1. Spherical mirror ki chamakdaar sateh kaisi hoti hai? (a) Bilkul sapaat (b) Khokhle gole ke tukde jaisi mudi (c) Teekhe konon wali (d) Khurduri
✅ (b): spherical mirror ki sateh gole ke tukde jaisi mudi hoti hai.
(a) sapaat sateh plane mirror ki hoti hai.
(c) mirror ki sateh mein kone nahi hote.
(d) khurduri sateh saaf image nahi banati, woh mirror hi nahi.
Q2. Concave mirror ki chamakdaar sateh: (a) bahar ki taraf ubhri (b) andar ki taraf dhansi (c) sapaat (d) dono taraf chamakdaar
✅ (b): con-cave, gufa ki tarah andar dhansi.
(a) bahar ubhri sateh convex mirror ki hai.
(c) sapaat sateh plane mirror ki hai.
(d) mirror ki ek hi taraf chamakdaar hoti hai, doosri peeth hoti hai.
Q3. Chammach ki peeth (ubhri taraf) mein chehra kaisa dikhta hai? (a) Ulta aur bada (b) Seedha aur chhota (c) Seedha aur barabar (d) Dikhta hi nahi
✅ (b): peeth convex mirror hai, jo hamesha seedha aur chhota image banata hai.
(a) ulta image chammach ke andar wali (concave) taraf thoda door se dikhta hai.
(c) barabar aur seedha image plane mirror banata hai.
(d) chamakdaar sateh hone se image zaroor dikhta hai.
Q4. Inme se kaunsa convex mirror ki tarah kaam karta hai? (a) Torch ka reflector (b) Dentist ka mirror (c) Scooter ka side mirror (d) Dressing table ka sheesha
✅ (c): side mirror convex hota hai.
(a) torch reflector concave hota hai.
(b) dentist ka mirror concave hai, daant bade dikhata hai.
(d) dressing table ka sheesha plane hai.
Q5. Ray diagram mein mirror ki tirchhi lakeeron wali (shaded) taraf kya batati hai? (a) Chamakdaar sateh (b) Na chamakne wali peeth (c) Roshni ka rasta (d) Mirror ka centre
✅ (b): shading peeche ki na chamakne wali taraf pe hoti hai.
(a) chamakdaar sateh bina shading ke hoti hai.
(c) roshni ka rasta teer wali line (ray) se dikhate hain.
(d) shading se centre nahi dikhaya jaata.
Q6. Mude kaanch ki ubhri (bahar wali) sateh pe chamakdaar parat lagai gayi. Kaunsa mirror banega? (a) Plane (b) Convex (c) Concave (d) Koi mirror nahi
✅ (c) Concave: parat wali taraf peeth ban jaati hai, toh roshni andar ki khokhli sateh se lautegi.
(a) sateh mudi hai, isliye plane nahi.
(b) convex tab banta jab parat andar ki sateh pe hoti.
(d) parat lagne se mirror zaroor banta hai.
Q7. Ek mirror mein, object ko door le jaane par bhi, image hamesha seedha aur barabar rehta hai. Mirror kaunsa hai? (a) Concave (b) Convex (c) Plane (d) Chammach ka andar
✅ (c) Plane: sirf plane mirror hamesha barabar aur seedha image deta hai.
(a) concave mein door jaane pe image ulta ho jaata hai.
(b) convex mein image chhota hota hai, barabar nahi.
(d) chammach ka andar concave hai.
Q8. Concave ka Hindi naam kya hai? (a) Uttal darpan (b) Samtal darpan (c) Avtal darpan (d) Golakaar lens
✅ (c) Avtal darpan.
(a) uttal darpan convex mirror hai.
(b) samtal darpan plane mirror hai.
(d) lens mirror nahi hota, aur woh agle posts ka topic hai.
🔗 Assertion–Reason
Options: (a) A aur R dono sahi, aur R, A ko samjhata hai · (b) A aur R dono sahi, par R, A ko nahi samjhata · (c) A sahi, R galat · (d) A galat, R sahi
1. A: Steel ki chammach ki do sateh do alag tarah ke mirror ki tarah kaam karti hain. R: Chammach ka andar wala hissa dhansa hua aur peeth ubhri hui hai.
✅ (a): dhansi sateh concave aur ubhri sateh convex ki tarah kaam karti hai, isliye R, A ko samjhata hai.
2. A: Convex mirror hamesha ulta image banata hai. R: Convex mirror ki chamakdaar sateh bahar ki taraf ubhri hoti hai.
✅ (d): A galat hai, convex mirror hamesha seedha (aur chhota) image banata hai. R sahi hai.
3. A: Spherical mirrors ko khokhle gole ka tukda maana jaata hai. R: Spherical mirrors asal mein kaanch ki gend kaat kar banaye jaate hain.
✅ (c): A sahi hai (shape samjhane ke liye aisa maante hain). R galat hai, mirror sapaat kaanch ko ghis aur polish karke banaye jaate hain.
📝 Very Short Answer (1 mark)
1. Spherical mirror ki paribhasha likho.
Jis mirror ki chamakdaar sateh khokhle gole ke tukde jaisi mudi ho, use spherical mirror kehte hain.
2. Concave mirror ka ek ghar ka example do.
Steel ki chammach ka andar wala hissa (ya torch ka reflector).
3. Convex mirror ka ek example do.
Scooter/car ka side mirror (ya chammach ki peeth).
4. Convex mirror ka Hindi naam likho.
Uttal darpan.
5. Plane mirror mein image kaisa banta hai?
Seedha (erect), object ke barabar size ka, aur laterally inverted.
📝 Short Answer (2–3 marks)
1. Concave aur convex mirror mein do antar likho.
(1) Concave ki chamakdaar sateh andar dhansi hoti hai; convex ki bahar ubhri. (2) Convex mirror hamesha seedha aur chhota image banata hai; concave mein paas se seedha-bada aur door se ulta image banta hai.
2. Bina chhue concave aur convex mirror kaise pehchanoge? Do tareeke batao.
(1) Mirror ko mez pe chamakdaar sateh upar karke rakho aur side se dekho: beech mein dhansi sateh concave, ubhri sateh convex. (2) Ek pencil ko mirror ke saamne paas se door le jao: image hamesha chhota-seedha rahe toh convex; paas se bada-seedha aur door se ulta ho toh concave.
3. Ray diagram mein concave aur convex mirror kaise banate hain?
Dono ko ek mudi line (arc) se dikhate hain aur peeche ki na chamakne wali taraf ko tirchhi lakeeron se shade karte hain. Concave mein dekhne wale ke liye arc khokhla dikhta hai (ubhri peeth shaded); convex mein arc dekhne wale ki taraf ubhra hota hai (khokhli peeth shaded).
4. Spherical mirror asal mein kaise banaye jaate hain?
Sapaat kaanch ke tukde ko ghis aur polish karke mudi shape di jaati hai. Phir ek taraf aluminium jaisi chamakdaar parat lagate hain. Parat ubhri sateh pe lage toh concave mirror, khokhli sateh pe lage toh convex mirror banta hai.
📝 Long Answer (5 marks)
1. Spherical mirror kya hai? Concave aur convex mirror ko diagram, examples aur image ki khoobiyon ke saath samjhao.
Spherical mirror: jis mirror ki chamakdaar sateh ek khokhle gole ke tukde jaisi mudi ho.
Concave mirror (avtal): chamakdaar sateh andar dhansi. Diagram mein arc dekhne wale ke liye khokhla, ubhri peeth shaded. Image: object paas ho toh seedha aur bada; door ho toh ulta. Examples: chammach ka andar, torch reflector, dentist mirror.
Convex mirror (uttal): chamakdaar sateh bahar ubhri. Diagram mein arc dekhne wale ki taraf ubhra, khokhli peeth shaded. Image: hamesha seedha aur chhota; zyada area dikhta hai. Examples: chammach ki peeth, gaadi ka side mirror, sadak ke mod ka sheesha.
Teeno mirrors (plane bhi) mein lateral inversion hota hai.
2. Chammach wali activity ka varnan karo: saamaan, steps, observation aur nishkarsh.
Saamaan: ek saaf chamakdaar steel ki chammach.
Steps: chammach ka andar wala hissa chehre se haath bhar door pakdo aur image dekho; phir paas-door karo; phir chammach palat kar peeth mein yahi dohrao; observations likho.
Observation: andar wali sateh mein (door se) chehra ulta dikhta hai; peeth mein seedha aur chhota, aur door karne pe thoda aur chhota.
Nishkarsh: mudi chamakdaar sateh bhi mirror hai. Andar dhansi sateh concave aur bahar ubhri sateh convex mirror ki tarah kaam karti hai, aur dono plane mirror se alag image banati hain.
📰 Case-Based Question
Rohan apne papa ke saath scooter ki dukaan gaya. Wahan usne dekha ki scooter ke side mirror mein peeche khadi badi bus bhi chhoti si dikh rahi thi, par peeche ki poori sadak nazar aa rahi thi. Dukaan wale ki mez pe ek purani torch khuli padi thi, jiske bulb ke peeche ek chamakdaar khokhli katori lagi thi. Ghar aakar Rohan ne steel ki katori ulti karke usme apna chehra dekha.
Q1. Scooter ka side mirror kaunsa mirror hai?
Convex mirror, kyunki image chhota aur seedha hai, aur zyada area dikhta hai.
Q2. Torch ke bulb ke peeche wali katori kaunsa mirror hai?
Concave mirror (iski chamakdaar sateh andar dhansi hai).
Q3. Ulti katori mein Rohan ka chehra kaisa dikha hoga? Kyun?
Seedha aur chhota, kyunki ulti katori ki bahar wali ubhri sateh convex mirror ki tarah kaam karti hai.
Q4. Side mirror mein bus chhoti dikhi. Kya bus sach mein door thi? Ek line mein samjhao.
Zaroori nahi. Convex mirror har cheez ka image chhota banata hai, isliye gaadiyan asal se door lag sakti hain. Isiliye drivers ko savdhan rehna chahiye.
🚀 HOTS
1. Ek mirror ko mez pe rakhne par woh bilkul sapaat lagta hai, par usme aapka image thoda chhota dikhta hai. Woh kaunsa mirror ho sakta hai? Kyun?
Woh ek bahut kam muda (bade gole ka tukda) convex mirror ho sakta hai. Bade gole ka tukda lagbhag sapaat dikhta hai, par convex hone se image phir bhi thoda chhota banata hai. Plane mirror hota toh image barabar hota.
2. Golu kehta hai, “Mere paas sirf ek mudi hui kaanch ki plate aur silver ki parat hai. Main concave aur convex dono mirror bana sakta hoon, par ek saath nahi.” Kya woh sahi hai?
Haan. Parat ubhri sateh pe lagaye toh concave, khokhli sateh pe lagaye toh convex banega. Ek plate ki ek hi taraf parat lag kar peeth banti hai, isliye ek samay mein ek hi tarah ka mirror banega.
3. Shaant taalab ka paani kaunse mirror jaisa kaam karta hai, aur chhoti ladoo jaisi chamakti gol steel ki gend kaunse?
Shaant paani lagbhag plane mirror jaisa (sapaat sateh). Chamakti gol gend ki bahar ki sateh convex mirror jaisi: usme image chhota aur seedha dikhega.
🏆 Olympiad Corner
1. Ek chamakdaar khokhli gend ke andar baith kar (soch ke) uski deewar mein dekho, aur phir bahar se. Andar aur bahar se woh sateh kramashah kaunse mirror hai? (a) Convex, concave (b) Concave, convex (c) Dono plane (d) Dono concave
✅ (b): andar se deewar dhansi hai (concave), bahar se ubhri (convex). (a) ulta kram hai. (c) sateh mudi hai, plane nahi. (d) bahar ki sateh concave nahi ho sakti.
2. Kaunse mirror mein, object kahin bhi ho, image kabhi bhi object se BADA nahi banta? (a) Sirf plane (b) Sirf convex (c) Plane aur convex dono (d) Concave
✅ (c): plane mein image barabar aur convex mein chhota banta hai, dono mein kabhi bada nahi. (a) aur (b) adhoore hain. (d) concave mein paas rakhi cheez ka image bada banta hai.
3. Ek student ne concave mirror ka diagram banaya aur shading khokhli taraf kar di. Iska matlab kya hoga? (a) Diagram sahi hai (b) Diagram ab convex mirror dikha raha hai (c) Diagram plane mirror dikha raha hai (d) Shading ka koi matlab nahi
✅ (b): shading peeth batati hai. Khokhli taraf shaded hai, toh chamakdaar sateh ubhri hui hai, jo convex mirror hai. (a) concave mein ubhri peeth shade hoti hai. (c) arc muda hai, plane nahi. (d) shading se hi chamakdaar taraf pata chalti hai.
Har option pe tap karo, turant pata chalega sahi ya galat.
Q1. Steel spoon ke andar wale part (jisme dal aati hai) se mirror ki tarah dekho. Yeh kaunsa mirror hai?
(a) Concave: shiny surface andar ki taraf dhansi
✅ Sahi! Spoon ka andar wala part cave jaisa andar dhansa hai: concave mirror.
(b) Convex
❌ Galat: Andar aur bahar reverse kar diye. Bahar ubhri back side convex hai; andar dhansa part concave.
(c) Plane
❌ Galat: Curved surface ko flat maana. Spoon curved hai, plane nahi.
(d) Koi mirror nahi, spoon steel ka hai
❌ Galat: Sirf glass ko mirror maana. Koi bhi shiny curved surface mirror ki tarah behave karti hai.
Q2. Curved glass ke piece ki andar wali (hollow) side pe shiny coating lagayi. Light kis side se lautegi, aur mirror kaunsa banega?
(a) Andar ki side se: concave
❌ Galat: Coating wali side ko shiny front maana. Coating back side hai; light bahar ki ubhri side se lautegi.
(b) Bahar ki ubhri side se: convex
✅ Sahi! Coating wali side mirror ki back side banti hai. Light bahar ki ubhri side se lautegi: convex.
(c) Plane mirror banega
❌ Galat: Curved glass ko plane maana. Glass curved hai: spherical mirror.
(d) Dono side se light lautegi
❌ Galat: Dono side shiny maani. Light sirf us side se lautti hai jo coating ke opposite hai.
Q3. Ek mirror bahut bade sphere ka piece hai, doosra chhoti ball ka. Kaunsa plane mirror jaisa lagega?
(a) Chhoti ball wala
❌ Galat: Size ka asar reverse kar diya. Chhoti ball ka piece zyada curved hota hai.
(b) Dono same curved hain
❌ Galat: Sphere ka size ignore kiya. Bada sphere = kam curved.
(c) Bade sphere wala: woh kam curved hai
✅ Sahi! Sphere jitna bada, uska piece utna kam curved: lagbhag flat, plane mirror jaisa.
(d) Koi nahi, spherical mirror kabhi plane jaisa nahi
❌ Galat: Bahut bade sphere wali baat bhool gaye. Bahut bada sphere ka piece lagbhag flat hota hai.
Q4. Spoon ka andar wala part, spoon ki back side, dressing table ka flat mirror, steel bowl ki bahar wali side: inme se kitne convex mirror ki tarah behave karte hain?
(a) 1
❌ Galat: Bowl ki bahar wali side bhool gaye: 1. Woh bhi bahar ubhri hai: 1 + 1 = 2.
(b) 3
❌ Galat: Spoon ke andar wale part ko bhi gina: 2 + 1 = 3. Woh andar dhansa hai: concave.
(c) 4
❌ Galat: Sab gin liye (4). Spoon ka andar concave hai, flat mirror plane: 4 − 2 = 2.
(d) 2
✅ Sahi! Bahar ubhri surface = convex: spoon ki back side (1) + bowl ki bahar side (1) = 2.
Q5. Concave aur convex mirror ka difference kis baat se pata chalta hai?
(a) Shiny surface andar dhansi (concave) ya bahar ubhri (convex)
✅ Sahi! Side se dekho: shiny surface cave jaisi andar = concave, bahar ubhri = convex.
(b) Size se: bada concave, chhota convex
❌ Galat: Size ko identify karne ka rule maana. Dono kisi bhi size ke ho sakte hain; surface ka curve dekho.
(c) Glass ki thickness se
❌ Galat: Glass ki thickness ko reason maana. Difference shiny surface ke andar ya bahar curve hone mein hai.
(d) Colour se
❌ Galat: Colour ko reason maana. Concave-convex shape ki baat hai, colour ki nahi.
📚 Aur Padho (External Reference)
- NCERT Class 8 Science Curiosity, Chapter 10 (official PDF)
- DIKSHA: Sarkar ka free learning platform, NCERT ke videos ke liye
💖 CharuMam Motivation
Ek hi chammach, aur do alag chehre: ek taraf ulta, ek taraf chhota. Chammach nahi badli, bas dekhne ki taraf badli.
Zindagi mein bhi aisa hi hota hai, beta. Koi mushkil sawaal ek taraf se “ulta” lagta hai, toh use palat ke doosri taraf se dekhiye. Aur kabhi khud ko chhota mehsoos karein, toh yaad rakhiye: convex mirror mein bus bhi chhoti dikhti hai, par asal mein woh badi hi hoti hai. Aap bhi utne hi bade aur kaabil hain jitne aap ho. Bas nazariya sahi rakhiye aur roz thoda seekhte rahiye. 🌱
— CharuMam
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