Spherical Mirrors ke Images (Kab Seedha, Kab Ulta?)
Karchhi ko door le jao toh chehra palat kyun jaata hai? 🥄🔄
🧭 Is Post Mein
📖 Kahani: Karchhi ka Jaadu
Sunday ki shaam thi. Mummy ne kitchen ke bartan dho kar shelf pe sajaaye the, sab chamak rahe the. Golu ne ek chamakti karchhi (ladle) uthayi aur uski khokhli taraf mein jhaanka.
“Didi, dekho! Karchhi naak ke paas laata hoon toh meri aankh itni badi dikhti hai, jaise bhaalu ki aankh!” Phir usne haath seedha karke karchhi door kar di. “Arre! Ab toh main ulta latak gaya, chamgaadad ki tarah!”
Priya didi ne steel ki katori ulti karke uski ubhri taraf mein dekha. “Mere yahan toh chehra hamesha chhota aur seedha hai. Paas laao ya door le jao, kabhi ulta nahi hota.”
Rohan bhaiya bole: “Toh Golu ki karchhi ‘mood’ badalti hai, aur Priya ki katori hamesha ek jaisi. Iska raaz hai object aur mirror ke beech ki doori.”
Pichhle post mein humne concave aur convex mirror pehchaanna seekha. Aaj dekhenge ki inme image kaisa banta hai, aur doori badalne se kya-kya badalta hai. 🔍
🎯 Is Post Mein Kya Seekhenge
- Image ko describe karne ke 3 sawaal: seedha ya ulta? bada, chhota ya barabar? daayaan-baayaan ulta?
- Concave mirror mein object paas aur door hone par image kaise badalta hai
- Convex mirror mein image hamesha seedha aur chhota kyun rehta hai
- Plane, concave aur convex mirror ke images ki tulna
- Sirf image dekh kar mirror ko kaise pehchaanein (NCERT Activity ke saath)
🧱 Basics: Pehle Yeh Aana Chahiye
1. Object (vastu): woh cheez jo mirror ke saamne rakhi hai, jaise khilona, pencil ya aapka chehra.
2. Image (pratibimb): mirror mein us cheez ki jo shakal dikhti hai.
3. Concave aur convex: concave mirror ki chamakdaar sateh andar dhansi hoti hai (chammach ka andar), convex ki bahar ubhri (chammach ki peeth). Yaad nahi? Post 1 dobara dekh lo: Spherical Mirrors Kya Hain?
4. Plane mirror ka image (Class 7 se): hamesha seedha, object ke barabar, aur daayaan-baayaan ulta (lateral inversion).
💡 Concept: Kis Mirror mein Kaisa Image?
Step 1: Image ko describe karne ke 3 sawaal. Jab bhi kisi mirror mein image dekho, yeh teen sawaal poochho:
❷ Size? Object se bada = enlarged, chhota = diminished, ya barabar (same size).
❸ Daayaan-baayaan ulta? Haan ho toh = lateral inversion.
Step 2: Plane mirror, sabse seedha-saadha. Object ko paas rakho ya door, image hamesha seedha aur barabar. Doori se kuch nahi badalta (bas image bhi utna hi peeche dikhta hai jitna object aage hai).
Step 3: Concave mirror, “mood badalne wala” mirror. Iska image object ki doori pe nirbhar karta hai:
🔹 Object ko dheere-dheere door le jao: ek doori ke baad image ulta ho jaata hai. Shuru mein yeh ulta image bada hota hai.
🔹 Object aur door: image ulta hi rehta hai aur chhota hota jaata hai.
Beech mein ek aisi doori bhi aati hai jahan image itna phail jaata hai ki dhundhla ho jaata hai aur saaf pehchaan mein nahi aata. Wahi woh jagah hai jahan image “palat” raha hai.
Step 4: Convex mirror, “hamesha ek jaisa” mirror. Object kahin bhi ho, image hamesha seedha aur chhota. Object door le jaane pe image thoda aur chhota ho jaata hai, bas. Kabhi ulta nahi, kabhi bada nahi.
Step 5: Lateral inversion teeno mein. Plane, concave aur convex, teeno mirrors ke images mein daayaan-baayaan ulta dikhta hai. Toh yeh mirror pehchaanne ka tareeka nahi hai.
Step 6: Image se mirror pehchaano! Ab ek detective trick mil gayi. Object ko mirror ke paas se door le jao aur dekho:
✔️ Image hamesha seedha aur hamesha barabar → plane.
✔️ Image hamesha seedha aur hamesha chhota → convex.
Kyun zaroori hai yeh? Kyunki mirror ka kaam (use) usi ke image se tay hota hai. Bada image chahiye (dentist) toh concave, zyada area chahiye (gaadi) toh convex. Yeh agle post ka topic hai.
Ek line mein: Plane = hamesha barabar; Convex = hamesha chhota-seedha; Concave = paas se bada-seedha, door se ulta.
🖼️ Diagrams: Picture se Samjho
🔐 Deep Concept: Concave Palat-ta Kyun Hai, Convex Kyun Nahi?
Raaz 1: Concave roshni ko “ikattha” karta hai. Concave mirror ki sateh andar dhansi hai, isliye usse takra kar lautne wali roshni ki kirnein ek-doosre ki taraf mud kar milne lagti hain. Jab object bahut paas hota hai, kirnein itna nahi mil paati, aur humein mirror ke peeche ek bada, seedha image dikhta hai (jaise magnifying glass). Jab object door hota hai, kirnein mirror ke saamne aapas mein milkar cross kar jaati hain. Cross karne ka matlab: upar se aayi roshni neeche chali jaati hai, aur neeche wali upar. Isiliye image ulta ho jaata hai!
Raaz 2: Convex roshni ko “phaila” deta hai. Convex ki ubhri sateh se lautne wali kirnein ek-doosre se door phail jaati hain, kabhi milti nahi. Isliye woh kabhi cross nahi karti, aur image kabhi ulta nahi hota. Phaili hui kirnon ki wajah se ek chhote se mirror mein bahut bada area sama jaata hai, par har cheez chhoti dikhti hai.
Raaz 3: Image “kahan” banta hai? Plane aur convex mirror ka image hamesha mirror ke andar (peeche) dikhta hai, jahan roshni asal mein jaati hi nahi. Concave mirror ka ulta image mirror ke saamne banta hai. Badi class mein inhe virtual aur real image kehte hain. Abhi bas itna yaad rakho: ulta image sirf concave hi banata hai.
✏️ Examples: Image dekho, Mirror batao
Size kabhi nahi badla, kabhi ulta nahi hua.
Paas se seedha aur bada image sirf concave deta hai.
Hamesha seedha aur chhota, convex ki pehchaan.
Ulta image sirf concave mein banta hai.
Bahar ubhri chamakdaar sateh convex ki tarah kaam karti hai.
Doori ke saath seedha se ulta hona, sirf concave mein hota hai.
⚖️ Difference Table: Teeno Mirrors ke Images
| Baat | Plane mirror | Concave mirror | Convex mirror |
|---|---|---|---|
| Object paas ho | Seedha, barabar | Seedha, bada | Seedha, chhota |
| Object door ho | Seedha, barabar | Ulta (pehle bada, phir chhota) | Seedha, aur chhota |
| Kabhi ulta? | Kabhi nahi | Haan, door se | Kabhi nahi |
| Size doori se badalta? | Nahi | Haan, bahut | Haan, thoda sa |
| Lateral inversion | Haan | Haan | Haan |
| Ghar ka example | Dressing table | Chammach/karchhi ka andar | Chammach/katori ki peeth |
🚫 Misconceptions: Log aisa sochte hain… lekin
❌ “Concave mirror hamesha bada image banata hai.”
✅ Sach: object bahut door ho toh concave ka image ulta aur chhota hota hai.
❌ “Convex mirror bhi door se ulta image deta hai.”
✅ Sach: convex mein image kabhi ulta nahi hota, chahe object kitna bhi door ho.
❌ “Plane mirror se door jao toh image chhota ho jaata hai.”
✅ Sach: image ka asli size barabar hi rehta hai. Door ki cheez humari aankh ko chhoti lagti hai, isliye aisa bhram hota hai.
❌ “Lateral inversion sirf plane mirror mein hota hai.”
✅ Sach: NCERT activity mein teeno mirrors (plane, concave, convex) ke images mein lateral inversion dikhta hai.
❌ “Concave mirror mein image ek jhatke mein ulta ho jaata hai.”
✅ Sach: pehle image bada hota jaata hai, phir ek doori pe dhundhla ho jaata hai, aur uske baad ulta dikhta hai.
🔤 Key Terms (Exam mein English shabd hi likhna)
❓ FAQs
1. Concave mirror mein image kis doori pe ulta hota hai?
Yeh mirror kitna muda hai, us pe nirbhar karta hai. Chammach jaisi bahut mudi cheez mein kuch hi centimetre door jaate hi image palat jaata hai; kam mude bade mirror mein yeh doori zyada hoti hai. Isiliye activity mein object ko dheere-dheere door le jaana hai.
2. Kya convex mirror mein image kabhi gaayab ho jaata hai?
Nahi. Object bahut door jaaye toh image bahut chhota ho jaata hai, par dikhta rehta hai. Convex mirror mein image hamesha seedha hota hai.
3. Kya concave mirror mein object ke barabar image ban sakta hai?
Haan, ek khaas doori pe ulta image object ke lagbhag barabar banta hai (us doori se paas wala ulta image bada aur door wala chhota hota hai). Iske baare mein aap badi classes mein detail se padhenge.
4. Agar teeno mirrors mein lateral inversion hota hai, toh mirror kaise pehchaanein?
Image ke seedha/ulta hone aur size se. Ulta hua toh concave; hamesha barabar toh plane; hamesha chhota toh convex.
5. Concave mirror wala ulta image dhundhla kyun lagta hai beech mein?
Ek khaas doori pe lautne wali kirnein na theek se milti hain na alag dikhti hain, isliye image bahut bada aur dhundhla ho jaata hai. Yeh concave mirror ke focus ke paas hota hai, jo hum Post 5 mein padhenge.
🧪 Activity (NCERT): Do Mirror, Ek Khilona
Saamaan: ek concave mirror, ek convex mirror (school lab se), mirrors ko khada rakhne ke liye do chhote lakdi ke block (ya kitaabon ka sahara), aur ek chhota khilona (jaise toy car ya chhoti gudiya).
Kya dikhega:
🔹 Convex: image hamesha seedha aur chhota. Door le jaane par thoda aur chhota.
🔹 Dono mein lateral inversion dikhta hai.
Nishkarsh: spherical mirrors plane mirror se alag bartaav karte hain. Inme image ka size object ki doori ke saath badalta hai, aur concave mirror mein image door se ulta bhi ho jaata hai. Isliye image dekh kar hi bataya ja sakta hai ki mirror plane hai, concave hai ya convex.
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? Khokhli taraf (concave) mein image doori se palat-ta hai, ubhri taraf (convex) mein kabhi nahi.
Ek kaagaz pe bade aksharon mein apna naam likho (jaise “PRIYA”). Ise steel ki ulti katori (convex) ke saamne pakdo. Naam chhota dikhega aur akshar daayein se baayein ulte dikhenge. Yahi lateral inversion hai, jo plane mirror jaisa hi convex mein bhi hota hai.
Ghar ke 4 chamakdaar bartan lo. Har ek mein ek pencil ko paas se door le jao aur score-card bharo: Seedha/Ulta · Bada/Chhota/Barabar. Phir flowchart (Diagram 3) se batao kaun sa bartan kaunse mirror jaisa hai.
🧠 Think Like a Scientist
Sawaal: School lab mein Rohan ko ek mirror mila jiska label mit gaya hai. Woh bahar se sapaat jaisa dikhta hai. Rohan kaise pata kare ki yeh plane hai, concave hai ya convex?
Scientist ka tareeka dekho
1. Observe (dekho): mirror lagbhag sapaat dikhta hai, aankh se moda hua pata nahi chalta.
2. Guess (anumaan): agar yeh concave hai toh object door le jaane pe image ulta hoga; agar convex hai toh image hamesha chhota rahega.
3. Test (jaanch): mirror ko block ke sahare khada karo. Ek pencil ko 3–4 cm se shuru karke dheere-dheere 1–2 metre tak door le jao, aur har baar image dekho.
4. Result: maan lo pencil paas se badi aur seedhi dikhi, aur kaafi door jaane pe ulti ho gayi.
5. Conclusion: mirror concave hai (kam muda hua, isliye sapaat jaisa lagta hai). Agar image hamesha barabar hota toh plane, aur hamesha chhota-seedha hota toh convex. 🔬
🌍 Real Life Mein
- 🦷 Dentist ka mirror: daant ke bilkul paas rakha concave mirror daant ka seedha aur bada image deta hai.
- 💄 Makeup / shaving mirror: paas se chehra bada dikhta hai, taaki chhoti cheezein saaf dikhein. Yeh concave hota hai.
- 🛵 Gaadi ke side mirror: convex, image hamesha seedha aur chhota, par peeche ki zyada sadak dikhti hai.
- ⛰️ Pahaadi mod aur dukaan ke kone ke gol sheeshe: convex, ek saath bada area dikhane ke liye.
- 🥄 Rasoi ke bartan: chammach, karchhi, katori, sab chhote-chhote concave aur convex mirrors hain!
In upyogon ko hum agle post mein aur detail se samjhenge.
🔁 Recap: Poora Post Ek Nazar Mein
- Image ke 3 sawaal: erect/inverted, enlarged/diminished/same size, lateral inversion.
- Plane: hamesha seedha aur barabar, doori se kuch nahi badalta.
- Concave: bahut paas se seedha aur bada; door le jaane par ulta (pehle bada, phir chhota hota jaata hai).
- Convex: hamesha seedha aur chhota; door jaane par thoda aur chhota.
- Ulta image sirf concave mein banta hai.
- Lateral inversion teeno mirrors mein dikhta hai.
- Image dekh kar mirror pehchaan sakte hain (flowchart yaad rakho).
✍️ Fill in the Blanks
- Sir upar wala seedha image ______ image kehlata hai.
- Object se chhote image ko ______ image kehte hain.
- Plane mirror mein image hamesha seedha aur object ke ______ hota hai.
- Convex mirror mein image hamesha seedha aur ______ hota hai.
- Concave mirror ke bahut paas rakhe object ka image seedha aur ______ hota hai.
- Ulta (inverted) image sirf ______ mirror mein banta hai.
Answers
1) erect (seedha) · 2) diminished (chhota) · 3) barabar (same size) · 4) chhota (diminished) · 5) bada (enlarged) · 6) concave
✅ True / False
- Convex mirror mein object door le jaane par image ulta ho jaata hai.
- Concave mirror mein image ka size object ki doori ke saath badalta hai.
- Plane mirror mein image hamesha object ke barabar hota hai.
- Lateral inversion sirf plane mirror mein dikhta hai.
- Concave mirror mein bahut door rakhe object ka image ulta aur chhota hota hai.
- Dentist daant ka bada image dekhne ke liye convex mirror use karta hai.
Answers (kyun ke saath)
1) False: convex mein image hamesha seedha rehta hai, bas thoda chhota hota hai.
2) True: paas se seedha-bada, door se ulta, aur aur door se ulta-chhota.
3) True: plane mirror ka image doori se nahi badalta.
4) False: teeno mirrors (plane, concave, convex) mein lateral inversion dikhta hai.
5) True: door jaate-jaate ulta image chhota hota jaata hai.
6) False: dentist concave mirror use karta hai, jo paas se bada aur seedha image deta hai.
🔘 MCQs
Q1. Plane mirror mein image kaisa hota hai? (a) Ulta aur chhota (b) Seedha aur barabar (c) Seedha aur bada (d) Ulta aur barabar
✅ (b): plane mirror hamesha seedha aur barabar image deta hai.
(a) plane mirror kabhi ulta ya chhota image nahi deta.
(c) bada image concave mirror paas se deta hai.
(d) plane mirror ka image ulta nahi hota.
Q2. Convex mirror ka image hamesha: (a) seedha aur chhota (b) ulta aur chhota (c) seedha aur bada (d) ulta aur bada
✅ (a): convex mirror kisi bhi doori pe seedha aur chhota image banata hai.
(b) convex mein image kabhi ulta nahi hota.
(c) convex kabhi bada image nahi deta.
(d) ulta aur bada image concave mein thodi doori pe banta hai.
Q3. Concave mirror se 3–4 cm door rakhe khilone ka image: (a) ulta aur chhota (b) ulta aur bada (c) seedha aur bada (d) seedha aur chhota
✅ (c): bahut paas rakhe object ka image seedha aur bada hota hai.
(a) ulta-chhota tab hota hai jab object bahut door ho.
(b) ulta-bada tab hota hai jab object thoda door ho.
(d) seedha-chhota image convex mirror deta hai.
Q4. Concave mirror ke saamne se object ko kaafi door le jaane par image: (a) seedha aur bada ho jaata hai (b) ulta ho jaata hai (c) hamesha ke liye gaayab ho jaata hai (d) seedha aur barabar ho jaata hai
✅ (b): ek doori ke baad concave ka image ulta ho jaata hai.
(a) seedha-bada image paas se banta hai, door se nahi.
(c) image gaayab nahi hota, beech mein bas dhundhla hota hai.
(d) seedha-barabar image plane mirror deta hai.
Q5. Kaunsa mirror ulta image bana sakta hai? (a) Plane (b) Convex (c) Concave (d) Koi nahi
✅ (c): sirf concave mirror, object door hone par, ulta image banata hai.
(a) plane ka image hamesha seedha.
(b) convex ka image hamesha seedha.
(d) concave ulta image bana sakta hai, isliye “koi nahi” galat.
Q6. Ek mirror mein image hamesha seedha rehta hai, aur object door le jaane par thoda chhota hota jaata hai. Mirror hai: (a) Plane (b) Concave (c) Dentist ka mirror (d) Convex
✅ (d): hamesha seedha aur doori ke saath thoda chhota, convex ki pehchaan.
(a) plane mein size kabhi nahi badalta.
(b) concave mein door se image ulta ho jaata hai.
(c) dentist ka mirror concave hota hai.
Q7. Lateral inversion kis mirror ke image mein dikhta hai? (a) Sirf plane (b) Sirf spherical (c) Plane, concave aur convex, teeno (d) Kisi mein nahi
✅ (c): NCERT activity se pata chalta hai ki teeno mein daayaan-baayaan ulta dikhta hai.
(a) aur (b) adhoore hain.
(d) galat, lateral inversion zaroor dikhta hai.
Q8. Makeup mirror mein paas se chehra seedha aur bada dikhta hai. Yeh kaunsa mirror hai? (a) Concave (b) Convex (c) Plane (d) Gaadi ka side mirror
✅ (a): paas se seedha-bada image sirf concave deta hai.
(b) convex hamesha chhota image deta hai.
(c) plane barabar image deta hai, bada nahi.
(d) side mirror convex hota hai, chhota image deta 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: Convex mirror mein kabhi ulta image nahi dikhta. R: Convex mirror hamesha seedha aur chhota image banata hai.
✅ (a): convex hamesha seedha image banata hai, isi wajah se usme kabhi ulta image nahi dikhta. R, A ko samjhata hai.
2. A: Concave mirror mein image ka size object ki doori ke saath badalta hai. R: Plane mirror mein image hamesha object ke barabar hota hai.
✅ (b): dono baatein sahi hain, par plane mirror ki baat concave mirror ke size badalne ki wajah nahi batati.
3. A: Sirf image dekh kar plane, concave aur convex mirror pehchaane ja sakte hain. R: Teeno mirrors hamesha ek jaisa image banate hain.
✅ (c): A sahi hai. R galat hai, teeno ke images alag hote hain, isi liye pehchaan sambhav hai.
📝 Very Short Answer (1 mark)
1. Erect image kise kehte hain?
Jo image seedha ho, yaani sir upar ki taraf, use erect image kehte hain.
2. Diminished image ka matlab kya hai?
Jo image object se chhota ho.
3. Kaunsa mirror hamesha seedha aur chhota image banata hai?
Convex mirror.
4. Concave mirror ke bahut paas rakhe object ka image kaisa hota hai?
Seedha (erect) aur bada (enlarged).
5. Lateral inversion kin mirrors mein dikhta hai?
Plane, concave aur convex, teeno mein.
📝 Short Answer (2–3 marks)
1. Concave mirror ke saamne object ko paas se door le jaane par image mein kya badlav aate hain?
Paas se image seedha aur bada hota hai. Door le jaane par ek doori pe image dhundhla hota hai aur phir ulta ho jaata hai. Shuru mein ulta image bada hota hai, aur object aur door jaane par chhota hota jaata hai.
2. Plane mirror aur convex mirror ke images mein do samaantayein aur ek antar likho.
Samaantayein: (1) dono mein image hamesha seedha hota hai; (2) dono mein lateral inversion hota hai. Antar: plane mirror ka image object ke barabar hota hai, jabki convex ka hamesha chhota.
3. Bina mirror chhue, sirf image dekh kar concave aur convex mirror kaise pehchanoge?
Ek object ko mirror ke paas se dheere-dheere door le jao. Agar image kisi doori pe ulta ho jaaye toh mirror concave hai. Agar image hamesha seedha aur chhota rahe toh convex hai.
4. Convex mirror mein image kabhi ulta kyun nahi hota? Saral shabdon mein samjhao.
Convex mirror ki ubhri sateh se lautne wali roshni ki kirnein ek-doosre se door phail jaati hain aur kabhi milti ya cross nahi karti. Cross na karne se upar-neeche ki adla-badli nahi hoti, isliye image hamesha seedha rehta hai (aur chhota bhi).
📝 Long Answer (5 marks)
1. Plane, concave aur convex mirror ke images ki tulna karo: object paas aur door hone par image seedha/ulta aur size kaisa hota hai? Ek-ek example bhi do.
Plane mirror: paas ho ya door, image hamesha seedha aur barabar. Example: dressing table ka sheesha.
Concave mirror: object bahut paas ho toh image seedha aur bada; object door le jaane par image ulta ho jaata hai, pehle bada aur phir chhota hota jaata hai. Example: dentist ka mirror, makeup mirror, chammach ka andar.
Convex mirror: image hamesha seedha aur chhota; object door jaane par thoda aur chhota. Example: gaadi ka side mirror, chammach ki peeth.
Teeno mein lateral inversion dikhta hai. Isliye image ke seedha/ulta aur size se mirror pehchaana ja sakta hai.
2. NCERT ki do-mirror wali activity ka varnan karo: saamaan, steps, observations aur nishkarsh.
Saamaan: concave mirror, convex mirror, do lakdi ke block, ek chhota khilona.
Steps: dono mirrors ko blocks ke sahare mez pe khada karo; khilona 3–4 cm door rakho aur dono images dekho; phir khilone ko dheere-dheere door le jao aur badlav note karo; har mirror ke saath alag se bhi dohrao.
Observations: concave mein paas se seedha-bada image, door le jaane par ulta, aur aur door jaane par ulta image chhota hota gaya. Convex mein image hamesha seedha aur chhota, door jaane par thoda aur chhota. Dono mein lateral inversion.
Nishkarsh: spherical mirrors plane mirror se alag hain; inme image ka size doori se badalta hai aur concave mein image ulta bhi ho sakta hai. Image dekh kar mirror ka prakar pehchaana ja sakta hai.
📰 Case-Based Question
Priya apni mausi ke beauty parlour gayi. Wahan ek chhota gol mirror tha jisme paas jaane par uska chehra seedha aur kaafi bada dikha. Deewar pe ek bada sapaat sheesha tha, jisme woh jitna bhi peeche gayi, uska image seedha aur uske barabar hi raha. Parlour ke ek kone mein upar ek ubhra hua gol sheesha laga tha, jisme poora parlour chhota-chhota sa dikh raha tha.
Q1. Chhota gol mirror, jisme chehra bada dikha, kaunsa mirror hai?
Concave mirror, kyunki paas se seedha aur bada image sirf concave deta hai.
Q2. Agar Priya us chhote gol mirror se kaafi door chali jaaye, toh uska image kaisa dikhega?
Ulta (inverted), aur bahut door hone par chhota bhi.
Q3. Kone wala ubhra sheesha kaunsa hai, aur usme poora parlour kyun dikhta hai?
Convex mirror. Yeh hamesha seedha aur chhota image banata hai aur ubhri sateh ki wajah se ek saath bada area dikhata hai.
Q4. Deewar ke sheeshe mein peeche jaane par bhi kya nahi badla, aur kyun?
Image ka seedha hona aur uska size (barabar) nahi badla, kyunki woh plane mirror hai.
🚀 HOTS
1. Ek mirror se 2 metre door khade hone par aapka image ulta dikhta hai. Kya woh plane ya convex mirror ho sakta hai? Kyun?
Nahi. Plane aur convex mirror hamesha seedha image banate hain. Ulta image sirf concave mirror bana sakta hai, isliye woh concave hai.
2. Side mirror mein peeche ki gaadi chhoti dikhti hai. Driver ke liye isme kya khatra ho sakta hai?
Convex mirror image ko chhota dikhata hai, isliye peeche ki gaadi asal se zyada door lag sakti hai. Driver galat andaza laga ke achanak mud sakta hai. Isliye mirror ke saath sir ghuma kar bhi dekhna aur savdhaan rehna zaroori hai.
3. Golu ek bade concave mirror ki taraf door se dheere-dheere chal kar aata hai. Uska image kis kram mein badlega?
Door se image ulta aur chhota; paas aate-aate ulta image bada hota jaayega; ek doori pe image dhundhla ho jaayega; aur bilkul paas aane par image seedha aur bada dikhega. (Yeh activity ka ulta kram hai.)
🏆 Olympiad Corner
1. Concave mirror ke saamne object ko paas se door le jaane par image ka sahi kram kya hai? (a) Seedha-bada → ulta-bada → ulta-chhota (b) Ulta-chhota → seedha-bada → seedha-chhota (c) Hamesha seedha-chhota (d) Hamesha ulta-barabar
✅ (a): paas se seedha-bada, phir ulta (pehle bada), phir ulta-chhota. (b) kram ulta hai aur seedha-chhota concave mein nahi banta. (c) yeh convex ka bartaav hai. (d) concave ka image doori se badalta hai.
2. Teen mirror P, Q, R. Object paas: P seedha-barabar, Q seedha-bada, R seedha-chhota. Object door: P seedha-barabar, Q ulta, R seedha-chhota. Pehchaano. (a) P convex, Q plane, R concave (b) P concave, Q convex, R plane (c) P plane, Q concave, R convex (d) P plane, Q convex, R concave
✅ (c): hamesha barabar = plane (P); ulta hua = concave (Q); hamesha chhota = convex (R). Baaki options mein kam se kam ek mirror galat pehchaana gaya hai.
3. Steel ki chammach ke andar aapko apna chehra ulta dikha. Chammach palat dene par chehra kaisa dikhega? (a) Ulta aur bada (b) Seedha aur chhota (c) Seedha aur bada (d) Kuch nahi dikhega
✅ (b): palatne par peeth (convex) saamne aati hai, jo hamesha seedha aur chhota image deti hai. (a) ulta image convex nahi banata. (c) bada image convex nahi banata. (d) chamakdaar sateh image zaroor banati hai.
Har option pe tap karo, turant pata chalega sahi ya galat.
Q1. Ek mirror mein object bahut paas ho to image erect aur enlarged; door le jao to inverted. Mirror kaunsa hai?
(a) Convex
❌ Galat: Convex ko inverted image wala maana. Convex ka image hamesha erect aur diminished.
(b) Concave
✅ Sahi! Paas se erect aur enlarged, door se inverted: yeh sirf concave mein hota hai.
(c) Plane
❌ Galat: Plane ko badalne wala maana. Plane ka image hamesha erect aur same size.
(d) Koi mirror aisa nahi karta
❌ Galat: Concave ka behaviour bhool gaye. Concave paas se erect-enlarged, door se inverted.
Q2. Object ko convex mirror se dheere-dheere door le jao. Image ka kya hoga?
(a) Inverted ho jaayega
❌ Galat: Concave wali baat convex pe lagayi. Convex kabhi inverted image nahi banata.
(b) Enlarged ho jaayega
❌ Galat: Convex ko enlarge karne wala maana. Convex ka image hamesha diminished.
(c) Erect hi rahega, thoda aur diminished
✅ Sahi! Convex: image hamesha erect aur diminished; door jaane pe thoda aur chhota.
(d) Same size ho jaayega
❌ Galat: Plane wali baat convex pe lagayi. Same size sirf plane mirror mein.
Q3. Plane mirror, concave (object bahut paas), concave (object door), convex: inme se kitne cases mein image erect hai?
(a) 2
❌ Galat: Concave (paas) ko chhod diya: 2. Paas se concave bhi erect deta hai: 2 + 1 = 3.
(b) 4
❌ Galat: Concave (door) ko bhi erect gina: 4. Door se concave inverted deta hai: 4 − 1 = 3.
(c) 1
❌ Galat: Sirf plane gina: 1. Concave paas aur convex bhi erect: 1 + 1 + 1 = 3.
(d) 3
✅ Sahi! Plane (1) + concave paas (1) + convex (1) = 3 erect. Concave door: inverted.
Q4. Plane mirror ke front mein khade hoke right hand uthaya. Image mein kaunsa hand utha dikhega?
(a) Left hand: lateral inversion (left-right reverse)
✅ Sahi! Mirror image mein left-right reverse dikhta hai (lateral inversion): right hand image ka left hand lagta hai.
(b) Right hand: image mein kuch reverse nahi hota
❌ Galat: Lateral inversion bhool gaye. Plane mirror mein left-right reverse dikhta hai.
(c) Right hand, par image inverted (upside down)
❌ Galat: Lateral inversion ko inverted samjha. Plane image erect hota hai; sirf left-right reverse.
(d) Lateral inversion sirf concave mein hota hai
❌ Galat: Lateral inversion ko ek mirror ka maana. Teeno mirrors mein hota hai.
Q5. Ek mirror mein image inverted aur diminished dikha. Mirror aur object ki position kya ho sakti hai?
(a) Convex, object door
❌ Galat: Convex ko inverted wala maana. Convex ka image hamesha erect.
(b) Concave, object kaafi door
✅ Sahi! Inverted sirf concave deta hai; object aur door jaaye to inverted image chhota (diminished) hota jaata hai.
(c) Concave, object bahut paas
❌ Galat: Paas wali position li. Bahut paas se concave image erect aur enlarged deta hai.
(d) Plane, object door
❌ Galat: Plane ko inverted maana. Plane ka image hamesha erect aur same size.
📚 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
Concave mirror ke paas jaao toh woh aapko bada dikhata hai, door jaao toh ulta. Mirror wahi hai, bas doori badli aur poori tasveer badal gayi.
Padhai ke saath bhi yahi rishta hai, beta. Jab hum kisi subject se door bhaagte hain, toh woh ulta aur mushkil lagta hai. Jab roz thoda-thoda uske paas aate hain, toh wahi subject seedha, saaf aur bada dikhne lagta hai, aur hum use pakad lete hain. Toh doori mat banaiye, roz das minute hi sahi, padhai ke paas aaiye. 🌱
— CharuMam
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