Sanvahan aur Hawaayein
Class 7 Science · Chapter 7: Prakriti mein Garmi ka Sthaanaantaran · NCERT Curiosity section 7.2
Seekho
Chulhe ka dhuaan oopar uthta. Kyun, ye jaanne Neel ek santulit dandi ke siron par do kaagaz ke cup ulte latkaata aur ek ke neeche surakshit doori par mombatti rakhta. Wo cup oopar uthta! Andar ki hawa garam hokar phailti, halki hokar oopar jaati, jaise dhoop mein rakha gubbaara phoolta.
Teacher ke saath wo paani ke beaker ke tal mein ek baingani crystal ka daana daalte aur neeche se garam karte. Rangeen dhaar beech se uthti aur kinaaron se utarti. Garam paani uthta, thanda bhaari paani uski jagah baithta, aur chakra chalta. Kanon ki asli chaal se le jaayi garmi sanvahan hai: drav aur gas aise garam hote.
Samudra tat par Zoya dhoop mein mitti aur paani ke katoron ko har 5 minute naapti. Mitti jaldi garam hoti paani se, aur andar jaldi thandi bhi. Din mein garam zameen ki hawa uthti aur samudra se thandi hawa aati: samudri hawa. Raat ko zameen thandi, samudra ki garam hawa uthti, aur hawa zameen se samudra ki or: zameeni hawa.
Explore: garmi kaun le jaata?
- Har ek sort karo.
Yaad rakho
- Sanvahan: drav aur gas mein kanon ki asli chaal se garmi; garam upar, thanda neeche.
- Zameen paani se jaldi garam-thandi, din mein samudri aur raat mein zameeni hawa.
Quick check
Din mein samudri hawa kyun chalti?
- zameen jaldi garam, uski garam hawa uthti aur thandi samudri hawa aati
- samudra jaldi garam
- Sooraj hawa dhakelta
- din mein sanvahan nahi
Answer
zameen jaldi garam, uski garam hawa uthti aur thandi samudri hawa aati. Raat ko ulta hota, zameeni hawa.
Socho
Room heater neeche aur AC deewaar par upar kyun lagaate?
Ek answer
Heater ki garam hawa uthkar kamre mein failti; AC ki thandi hawa neeche baithti. Dono sanvahan se hawa milaate.
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.