Class 8 Science Chapter 10: Light: Mirrors and Lenses (Hinglish Notes)
Ye chapter 5 lines mein
Light: Mirrors and Lenses mude hue darpan aur lens samjhaata hai. Avtal (concave) darpan andar ki or muda hota hai aur bada ya ulta pratibimb de sakta hai; uttal (convex) darpan baahar ubhra hota hai aur hamesha chhota, seedha pratibimb deta hai. Har darpan paraavartan ke niyam maanta hai. Uttal lens beech mein mota hota hai aur prakaash ko milaata hai; avtal lens kinaaron par mota hota hai aur failaata hai.
Ye chapter kis baare mein hai?
Ek science centre mein Meena mude hue darpanon ki ek qataar mein jhaankti hai. Ek mein uska chehra bahut bada dikhta hai, door khada bhai ulta dikhta hai, aur ek aur darpan nanhi Meena dikhaata hai. Samtal darpan kabhi aisa nahi karta. Ye golaakaar darpan hain, aur chapter inhe samjhaata hai, wo niyam jo har darpan maanta hai, aur unke rishtedaar, lens, jinme hum jhaankte nahi, jinse hokar dekhte hain.
Golaakaar darpan
Chamakta chammach achhi shuruaat hai (Activity 10.1). Uska khokhla andar ka hissa chehra ulta dikhaata hai; ubhra peechhe ka hissa seedha par chhota. Golaakaar darpan ki paraavartak sateh khokhle gole ke hisse jaisi hoti hai. Andar mudi ho to avtal darpan; baahar ubhri ho to uttal darpan. Mez par bagal se dekhne par antar saaf dikhta hai (Activity 10.2). Ye darpan kaanch ke gole ko kaatkar nahi bante: samtal kaanch ko ghiskar mod diya jaata hai aur aluminium jaisi parat chadhaayi jaati hai. Padho golaakaar darpan.
Ye kaise pratibimb banaate hain
Avtal aur uttal darpan ke saamne ek khilauna rakho aur use door le jaao (Activity 10.3). Avtal darpan mein paas ki vastu ka pratibimb seedha aur bada hota hai; door hone par ulta, pehle bada aur phir chhota. Uttal darpan ka pratibimb hamesha seedha aur chhota rehta hai, vastu door jaane par thoda aur chhota. Samtal darpan hamesha barabar size ka seedha pratibimb deta hai. Teeno paarshv parivartan dikhaate hain.
Kaam par darpan
Avtal darpan torch aur gaadi ki headlight ke reflector, daant badhaakar dikhaane wala dentist ka chhota darpan, aur zyaadatar aadhunik doorbeenon ka mukhya darpan banaate hain. Uttal darpan gaadiyon ke side-view mirror, tez modon aur chauraahon par, aur badi dukaanon mein lagte hain, kyunki ye kahin zyada chaude kshetra ka seedha pratibimb dete hain. Isiliye side-view mirror chetaata hai ki cheezein dikhne se zyada paas hain.
Paraavartan ke niyam
Prakaash ko hum kiranon se dikhaate hain, teer wali seedhi rekhaayein. Darpan par padne wali kiran aapatit kiran, lautne wali paraavartit kiran, aur jahan kiran takraati hai wahan darpan par 90° ki rekha abhilamb hai. Abhilamb ke saath bane kon aapatan kon (i) aur paraavartan kon (r) hain. Naapne par (Activity 10.4) i = r milta hai. Kaagaz modne se pata chalta hai ki aapatit kiran, abhilamb aur paraavartit kiran ek hi tal mein hain (Activity 10.5). Dono niyam samtal aur golaakaar darpanon par laagu hote hain. Padho paraavartan ke niyam.
Prakaash ko ikattha karna
Alag darpanon par kai samaanaantar kirnein bhejo (Activity 10.6). Samtal darpan se ve samaanaantar rehti hain; avtal darpan unhe milaata hai; uttal darpan unhe failaata hai. Suraj ki or kiya avtal darpan dhoop ko ek chamakte bindu par ikattha karke kaagaz se dhuaan nikaal sakta hai (Activity 10.7). Saur sandrak isi vichaar se bhaap banaate, khaana pakaate aur steel tak pighlaate hain.
Lens
Tel lagi plastic ki patti par paani ki boond neeche ke akshar bade dikhaati hai (Activity 10.8): ye ek saada lens ki tarah kaam karti hai. Lens mudi sathon wala paardarshi kaanch ya plastic ka tukda hai. Uttal lens beech mein mota hota hai; avtal lens kinaaron par mota. Uttal lens se paas ki vastu seedhi aur badi, door ki ulti dikhti hai; avtal lens se vastuein hamesha seedhi aur chhoti dikhti hain (Activity 10.9). Uttal lens samaanaantar kirnon ko milaata hai aur avtal lens failaata hai (Activity 10.10). Padho lens kya hai.
Kaam par lens
Uttal lens dhoop ko ikattha karke kaagaz jala sakta hai (Activity 10.11). Lens chashmon, camera, doorbeen aur microscope mein hote hain, aur hamari aankh mein bhi ek uttal lens hai jo apna aakaar badalta hai taaki hum paas aur door dono dekh sakein.
Aage badhne se pehle
800 se zyada saal pehle, Bhaskara II ke samay, khagolvid shaant paani ke katore mein taaron ka pratibimb tirchhi naliyon se dekhkar unki sthiti naapte the, yaani paraavartan ka vyavhaarik upyog karte the. Har sawaal ka jawaab Chapter 10 ke NCERT solutions mein hai.
Key terms (zaroori shabd)
| Term | Matlab |
|---|---|
| Golaakaar darpan (spherical mirror) | Aisa darpan jiski chamakti sateh khokhle gole ke hisse jaisi mudi ho. |
| Avtal darpan (concave mirror) | Golaakaar darpan jiski paraavartak sateh andar ki or mudi ho, jaise chammach ka andar ka hissa. |
| Uttal darpan (convex mirror) | Golaakaar darpan jiski paraavartak sateh baahar ki or ubhri ho, jaise chammach ka peechhe ka hissa. |
| Seedha aur ulta | Seedha (erect) pratibimb sahi taraf upar hota hai; ulta (inverted) pratibimb ulta hota hai. |
| Bada aur chhota | Bada (enlarged) pratibimb vastu se bada hota hai; chhota (diminished) usse chhota. |
| Paarshv parivartan (lateral inversion) | Darpan ke pratibimb mein baayein aur daayein ka badal jaana. |
| Aapatit aur paraavartit kiran | Darpan par padne wali prakaash ki kiran, aur usse lautne wali kiran. |
| Abhilamb (normal) | Jahan kiran darpan se takraati hai wahan darpan par 90° par kheenchi rekha. |
| Aapatan kon (i) aur paraavartan kon (r) | Aapatit kiran aur paraavartit kiran abhilamb ke saath jo kon banaati hain. |
| Milaana aur failaana (converge, diverge) | Prakaash ki kirnon ko paas laana, ya door failaana. |
| Lens | Mudi hui sathon wala paardarshi kaanch ya plastic ka tukda, jisse prakaash guzarta hai. |
| Uttal lens (convex lens) | Kinaaron se beech mein mota lens; prakaash ko milaane wala (converging) lens. |
| Avtal lens (concave lens) | Beech se kinaaron par mota lens; prakaash ko failaane wala (diverging) lens. |
| Saur sandrak (solar concentrator) | Darpan ya lens se dhoop ko chhoti jagah par ikattha karke garmi paane wala upkaran. |
Is chapter ke topics
Practice karo
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Chamakte chammach ka andar ka khokhla hissa kya banta hai?
Jawab dekho
Jawab: (b) avtal darpan
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Kaun sa darpan hamesha seedha, chhota pratibimb deta hai?
Jawab dekho
Jawab: (c) uttal
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Kiran darpan par abhilamb se 30° par padti hai. Paraavartan kon hai:
Jawab dekho
Jawab: (a) 30°
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Kaun sa lens beech se kinaaron par mota hota hai?
Jawab dekho
Jawab: (b) avtal lens
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Dentist avtal darpan kyon lete hain?
Jawab dekho
Jawab: (b) paas rakhne par bada drishya deta hai
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Uttal lens se guzarne wali samaanaantar kirnein:
Jawab dekho
Jawab: (b) mil jaati hain
Students ke sawal
Class 8 Science Chapter 10 ke mukhya topics kya hain?
Golaakaar darpan, avtal aur uttal, aur unhe pehchaanna; unke pratibimb; unke upyog; paraavartan ke do niyam; avtal aur uttal darpan prakaash ko kaise milaate aur failaate hain; lens, uttal aur avtal; unse dikhne wale pratibimb; aur magnifying glass se insaani aankh tak unke upyog.
Kya Light: Mirrors and Lenses naye NCERT Class 8 Science book mein hai?
Haan. Ye Curiosity, Class 8 Science textbook (Reprint 2026-27) ka Chapter 10 hai, pages 152 se 169 tak. Ye Class 7 ki ‘Light: Shadows and Reflections’ par aage banta hai.
Side-view mirror par ‘Objects in mirror are closer than they appear’ kyon likha hota hai?
Side-view mirror uttal hote hain. Ve peechhe ki sadak ka chauda drishya dikhaate hain, par har pratibimb asli gaadi se chhota hota hai, isliye gaadiyaan asal se door lagti hain. Ye chetaavni driver ko yaad dilaati hai.
Darpan aur lens mein kya antar hai?
Darpan prakaash ko lautaata hai, isliye hum pratibimb usmein dekhte hain. Lens paardarshi hota hai aur prakaash ko modkar guzarne deta hai, isliye hum cheezein usse hokar dekhte hain. Dono avtal ya uttal ho sakte hain, aur dono cheezon ko bada ya chhota dikha sakte hain.
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