Class 7 Science Chapter 11 NCERT Solutions Hinglish mein: Light: Shadows and Reflections

Curiosity, Class 7 Science ki textbook (Reprint 2026-27), ke Chapter 11, Light: Shadows and Reflections, ke har sawaal ka jawab: text ke sawaal, Activities 11.1–11.10 sample observations ke saath, Dive Deeper boxes, “Let Us Enhance Our Learning” ke saare 12 sawaal aur exploratory projects. Page numbers book ke hisaab se hain (pages 153–168). Short notes: Chapter 11 ke notes.

Keshav ke sawaal (page 153)

Kya Moon apni roshni banata hai? Nahi. Moon non-luminous hai: wo sirf apne upar padne waali dhoop ko reflect karke chamakta hai, isliye chaandni bas reflect hui dhoop hai. Grah bhi reflect hui dhoop se chamakte hain.

Kaun si cheezein apni roshni deti hain? Luminous cheezein, jaise Sun aur doosre taare, aasmaani bijli, aag, jugnu jaise chamakne waale jaanwar, aur bijli ke lamp.

Kya roshni seedhi line mein chalti hai? (pages 155–156)

Activity 11.1: ek maachis ka dabba thoda khiskaane pe kya screen pe spot milta hai? Nahi. Teeno chhed ek seedhi line mein hon to torch ki roshni sabse guzarkar chamakdaar spot banati hai. Ek dabba hilne pe uska chhed line se bahar ho jaata hai, roshni cardboard se takraati hai aur spot gaayab ho jaata hai. Isliye roshni seedhi line mein chalti hai.

Activity 11.2: kya mudi pipe se moambatti ki lau dikhti hai? Nahi. Seedhi pipe se lau dikhti hai, par mudi pipe mein lau se aankh tak koi seedha raasta nahi hota. Matlab roshni seedhi lakeeron mein hi chal rahi hai.

Dive Deeper: ek boond doodh waale paani mein laser. Doodh se laser ki dhaar dikhne lagti hai, aur wo paani mein seedhi raah pe chalti hai.

Transparent, translucent aur opaque cheezein (pages 156–157)

Activity 11.3: Table 11.1 ke sample observations.

Cheez	Roshni kitni guzarti hai; prakaar
Cardboard	bilkul nahi; opaque
Copy ka kaagaz	thodi; translucent
Kaanch	lagbhag poori; transparent
Tracing paper	thodi; translucent
Mota kapda	bilkul nahi; opaque
Saaf plastic sheet	lagbhag poori; transparent

Kya observation tumhare andaaze jaisa tha? Kya nateeja nikla? Zyaadatar haan, haalaanki patla kaagaz aksar hairaan karta hai kyunki wo thodi roshni jaane deta hai. Nateeja: transparent cheez se lagbhag saari roshni guzarti hai, translucent se thodi aur opaque se bilkul nahi.

Parchhaai banna (pages 157–159)

Roshni ke raaste mein opaque cheez rakhne pe screen pe kya dikha, aur kyun? Ek andhera hissa, yaani parchhaai. Roshni seedhi line mein chalti hai, isliye opaque cheez use rok leti hai, aur cheez ke peechhe ki jagah, jahan roshni nahi pahunchti, andheri rehti hai.

Kya translucent aur transparent cheezein parchhaai banati hain? Translucent cheezein halki parchhaai banati hain, aur kuch transparent cheezein feeki parchhaai. Opaque cheezein sabse gehri parchhaai banati hain.

Activity 11.4: Table 11.2 ke sample observations.

Kya kiya	Parchhaai ke baare mein observation
Screen hata di	Screen pe parchhaai nahi; wo peechhe jo bhi ho, jaise door ki deewar, us pe padti hai
Cheez hata di	Parchhaai nahi; sirf roshni ka chamakdaar hissa
Torch band ki	Parchhaai nahi, kyunki roshni hi nahi
Cheez screen ke paas le gaye	Parchhaai chhoti aur saaf hui
Cheez torch ke paas le gaye	Parchhaai badi aur dhundhli hui
Cheez jhukaayi	Parchhaai ka aakaar badal gaya
Cheez ka rang badla	Parchhaai kaali hi rahi; uska rang nahi badla

Parchhaai dekhne ke liye kya chahiye? Kya cheez ka rang badalne se parchhaai ka rang badalta hai? Teen cheezein: roshni ka srot, opaque cheez aur parchhaai pakadne ke liye screen. Parchhaai kitni badi, kis aakaar ki aur kitni saaf hogi, ye roshni aur screen ke beech cheez ki jagah pe nirbhar hai, par cheez kisi bhi rang ki ho, parchhaai kaali hi rehti hai.

Reflection of light (pages 159–160)

Chamakdaar steel ki thaali ne parchhaai bhi di aur saamne ki deewar pe chamakdaar spot bhi. Kyun? Thaali opaque hai, isliye parchhaai banati hai, par uski chamakdaar satah us pe padne waali roshni ko reflect bhi karti hai, aur chamakdaar spot saamne ki deewar pe bhejti hai.

Activity 11.5: jis deewar pe dhoop nahi padti, us pe dhoop kaise bhejein? Mirror ya chamakdaar thaali ko aise ghumaao ki usse reflect hui roshni us deewar pe pade. Chamakdaar spot banta hai, jo dikhaata hai ki mirror ne roshni ki disha badal di. Mirror jhukaane pe spot khisakta hai.

Activity 11.6: patli dhaar ke raaste mein mirror rakhne pe kya hota hai? Mirror se takraakar dhaar ki disha badal jaati hai. Mirror dwara roshni ke is mudne ko hum reflection of light kehte hain.

Kya mirror mein apna chehra dikhna bhi reflection ki wajah se hai? Haan. Tumhare chehre ki roshni mirror pe padti hai aur reflect hokar tumhari aankhon mein aati hai, isliye tumhe apna image dikhta hai.

Plane mirror mein image (pages 161–162)

Activity 11.7. Mirror ke peechhe ek pen khada dikhta hai: wahi uska image hai. Har jagah image pen ke same size ka aur erect hota hai, nok upar. Mirror ke peechhe ya aage rakhi screen pe image kabhi nahi aata, isliye plane mirror ka image screen pe kabhi nahi pakda ja sakta.

Activity 11.8: mirror se tumhari doori aur image ki doori mein kya sambandh hai? Dono barabar hain: image mirror ke peechhe utna hi door hai jitna tum aage ho. Paas jaao to image paas aata hai; peechhe hato to door jaata hai.

Left haath uthaao; right kaan chhuo. Image apni right taraf ka haath uthaata hai aur apna left kaan chhoota hai. Left aur right badal jaate hain: ye lateral inversion hai.

Ambulance pe AMBULANCE ulta kyun likha hota hai? Shabd laterally inverted likha jaata hai, taaki aage ke drivers jab use apne rear-view mirror mein dekhein, to mirror use phir se palat de aur wo AMBULANCE padha jaaye, aur wo jaldi raasta de sakein.

Kya image sirf mirror mein dikhte hain? Nahi. Thehre paani, chamakdaar steel aur khidki ke kaanch mein bhi image dikhte hain, aur pinhole camera screen pe image banata hai.

Pinhole camera (pages 162–164)

Activity 11.9: screen pe kya dikhta hai? Moambatti ki lau ka image, aur wo ulta, yaani inverted hai, kyunki lau ke upar aur neeche ki roshni seedhi lakeeron mein chalti hai jo chhed pe ek doosre ko kaatti hain.

Activity 11.10: kya image mein cheezon ke rang dikhte hain? Kya wo seedhe hain ya ulte? Image mein cheezon ke rang dikhte hain, aur wo ulte hote hain.

Kaam ki cheezein banaana (pages 164–165)

Periscope mein Z aakaar ke dabbe mein do plane mirror lage hote hain, jo wo cheezein dikhaate hain jo seedhe nahi dikhti, jaise submarine aur tank mein. Kaleidoscope mein triangle mein jude teen mirror hote hain; rangeen tukdon ke reflection ke reflection har baar ghumaane pe naya design banaate hain.

Let Us Enhance Our Learning (pages 165–167)

1. Kaun si cheezein luminous hain? Sun aur Pole Star, jo taare hain aur apni roshni dete hain. Mars, Moon aur Venus reflect hui dhoop se chamakte hain, aur mirror sirf roshni reflect karta hai, isliye ye non-luminous hain.

2. Columns milaao. Pinhole camera – ulta image banata hai; Opaque cheez – roshni ko poori tarah rokti hai; Transparent cheez – roshni lagbhag poori guzarti hai; Parchhaai – cheez ke peechhe bana andhera hissa.

3. Pipe se moambatti ki lau kaun dekh sakta hai? Rekha. Uski pipe ek seedhi line mein lau tak jaati hai. Sahil aur Patrick ki pipe tirchhe kone pe judti hain aur Qasima ki seedhe kone (90°) pe, isliye unki aankhon tak koi seedha raasta nahi pahunchta, aur roshni sirf seedhi line mein chalti hai.

4. Kaunsi tasveer ladke ki parchhaai sahi dikhaati hai? (d). Parchhaai roshni ke srot ki ulti taraf padti hai. (d) mein Sun right mein upar hai aur parchhaai left ki taraf phaili hai. (a) mein Sun lagbhag seedhe ladke ke peechhe hai, to parchhaai seedhe hamari taraf aani chahiye, side mein nahi; (b) mein parchhaai pairon ke theek neeche hai, jiske liye Sun sir ke upar hona chahiye; aur (c) mein Sun right mein hai par parchhaai seedhe hamari taraf aa rahi hai.

5. Kaunsi parchhaai kis scenario ki hai? Scenario (i), jisme gend torch ke paas hai, badi parchhaai, (b) deta hai. Scenario (ii), jisme gend deewar ke paas hai, chhoti parchhaai, (a) deta hai.

6. Torch ki jagah ko parchhaai se milaao. Torch gend ke paas – parchhaai badi hogi; torch door – parchhaai chhoti hogi; gend hata di – screen pe chamakdaar spot dikhega; gend ke left mein do torch – screen pe do parchhaaiyan dikhengi.

7. Pinhole camera mein ped ka image banaao. Image ulta hota hai: tana upar aur nukeela hissa neeche ki taraf (aur left-right bhi badal jaate hain).

8. Plane mirror mein tumhara naam. Image mein naam left se right ulta dikhta hai: akshar ulte kram mein aate hain aur har akshar palta hua hota hai, isliye “NEHA” ek ulta likha shabd lagta hai. Kaaran hai lateral inversion: plane mirror left aur right badal deta hai. Likhaavat upar-neeche ulti nahi hoti, kyunki plane mirror ka image erect hota hai.

9. Subah 9 baje, dopahar 12 baje aur shaam 4 baje tumhari parchhaai. Uttar India mein October ke aakhir mein 1.4 m lambe student ke sample observations: 9 baje lagbhag 2 m, 12 baje lagbhag 1 m aur 4 baje lagbhag 3.5 m; tumhare numbers jagah aur mausam pe nirbhar karenge. (i) Parchhaai 12 baje sabse chhoti hoti hai. (ii) Dopahar mein Sun aasmaan mein sabse upar hota hai, isliye uski roshni seedhe neeche padti hai aur parchhaai chhoti hoti hai; subah aur shaam ko Sun neeche hota hai, roshni tirchhi aati hai aur parchhaai lambi khinch jaati hai.

10. Statement A aur B. (i) Dono statements sach hain. Plane mirror ka image laterally inverted hota hai, aur T aur O mirror mein waise hi dikhte hain kyunki dono apni beech ki khadi line ke dono taraf ek jaise hain, isliye left-right badalne se kuch nahi badalta.

11. Kya bracket jaisi nali se periscope ban sakta hai? Mirror kahan lagenge? Haan. Nali ke har mod pe ek plane mirror 45° pe lagao: upar ke mod pe aise jhuka hua ki upar ke munh se aayi roshni nali mein neeche jaaye, aur neeche ke mod pe aise ki roshni neeche ke munh se bahar nikle. Neeche ke munh mein jhaankne pe tumhe wo dikhta hai jo upar ke munh ke saamne hai. Mirror ko bas mod dhakna hai, isliye nali ki chaudai se chhote mirror bhi kaam karte hain.

12. Oonchi udti chidiya ki parchhaai kyun nahi dikhti, par neeche jhapatne pe dikhti hai? Parchhaai kitni saaf aur gehri hogi, ye roshni aur screen ke beech cheez ki jagah pe nirbhar hai. Jab chidiya zameen ke paas hoti hai, uski parchhaai gehri aur saaf hoti hai. Jab wo aasmaan mein oonchi, zameen se door hoti hai, to parchhaai phailkar ek bahut feeka, dhundhla dhabba ban jaati hai jo dikhta nahi. (Extra) Aisa isliye hota hai kyunki Sun ek bindu nahi, ek chauda srot hai, to Sun ke alag alag hisson ki roshni zameen pe thodi alag dishaon se aakar chhoti aur door ki cheez ki parchhaai ko bhar deti hai.

Exploratory Projects (pages 167–168)

Tumhare yahan jugnu. Bado se poochho ki kya pehle jugnu aam the. Agar ab kam dikhte hain, to chapter ke bataaye kaaran hain light pollution, jungle ka kam hona aur bahut zyaada sailaani; (Extra) keetnaashak aur geeli ghaas waali zameen ka sookhna bhi unhe nuksaan pahunchaata hai. Jo seekho use ek chhoti kahani mein badlo, jaise ek bachcha jo gaon ko raat mein faltu lights band karne ke liye manaata hai.

Torch pe rangeen transparent kaagaz. Screen ka roshan hissa kaagaz ke rang ka ho jaata hai, par parchhaai kaali hi rehti hai: parchhaai tak roshni pahunchti hi nahi, uska rang kuch bhi ho. Alag rang ke kaagaz se roshan hissa rang badalta hai, parchhaai nahi.

Kone pe ya parallel rakhe do mirror. Kone pe rakhe do mirror kai image dikhaate hain, aur kona chhota karne pe image badhte hain. Aamne saamne parallel mirror images ki ek lambi kataar dikhaate hain, har agla pichhle se feeka. (Extra) θ kone pe rakhe mirror mein image ki ginti lagbhag 360°/θ − 1 hoti hai, jaise 90° pe 3 aur 60° pe 5 image.

Kya mirror ka chhota tukda poora bada ped dikha sakta hai? Haan, agar tum kaafi peechhe khade ho aur sahi kone se dekho. Image mirror ke peechhe utna hi door hota hai jitna ped aage, isliye wo itna chhota dikhta hai ki chhote mirror mein samaa jaata hai, jaise jeb ke mirror mein poora pahaad samaa jaata hai.