Roshni ke Srot aur Uska Chalna

Class 7 Science · Chapter 11: Roshni: Chhaaya aur Paraavartan · NCERT Curiosity section 11.1–11.3

Seekho

Garmi mein pahaadi gaanv ki yaatra par Neel aur Kabir andhere mein saikdon jugnu chamakte dekhte. Ghar lautti bus mein Neel chaandni mein pahaad aur guzarti gaadiyon ki roshni ki kiranein dekhta. "Kya Chaand apni roshni banaata?" wo sochta. "Aur wo kiranein itni seedhi kyun dikhti?"

Jo cheezein apni roshni deti wo deeptimaan: Sooraj, taare, aag, bijli, jugnu, aur lamp. Jo nahi deti wo adeeptimaan. Chaand adeeptimaan: chaandni usse lauti dhoop hai. LED lamp kam bijli mein tez roshni dete aur der tak chalte; puraane recycle karne chahiye, kachre mein nahi.

Neel teen maachis ki dibbiyan ek hi oonchaai ke chhedon ke saath line mein rakhkar torch daalta: card par tez dhabba. Ek dibbi thodi khiskaao aur dhabba gaayab. Mombatti ki lau seedhi nali se dikhti, mudi se nahi. Roshni seedhi rekha mein chalti.

Padaarth roshni alag-alag paar karne dete. Paardarshi (saaf kaanch, paani) lagbhag saari roshni jaane dete; paarbhaasi (tracing paper, ghisa kaanch) kuch; apaardarshi (gatta, lakdi, dhaatu) poori rok dete.

Explore: kya roshni paar hoti?

1. Har padaarth jaanchkar sort karo.

Yaad rakho

• Deeptimaan apni roshni dete; Chaand sirf dhoop lautaata.
• Roshni seedhi rekha mein; padaarth paardarshi, paarbhaasi ya apaardarshi.

Quick check

Mudi nali se mombatti ki lau kyun nahi dikhti?

1. roshni seedhi rekha mein chalti
2. nali garmi sokhti
3. lau bujh jaati
4. nali deeptimaan

Socho

Kai jagah jugnu kam kyun ho rahe?

Practice

Teen levels (easy, medium, hard) ke naye sawaalon se practice karo, kuch hands-on, hints aur hal ke saath. Topic poora karne ke liye pichhle 5 mein se 4 sahi karo.