Vikiran
Class 7 Science · Chapter 7: Prakriti mein Garmi ka Sthaanaantaran · NCERT Curiosity section 7.3
Seekho
Aag ke paas baithi Zoya chehre par garmi mehsoos karti, jabki wo use chhoo nahi rahi aur garam hawa usse door upar ja rahi. Garmi seedhe vikiran se pahunch rahi. Vikiran ko koi maadhyam nahi chahiye: isi se Sooraj ki garmi khaali antariksh paar karke Prithvi ko garam karti.
Har cheez garmi vikirit karti: chulhe se utaari garam kadaahi aas-paas garmi dekar thandi hoti. Rang ka asar: halke rang zyaadatar garmi lautaate, isliye safed kapde garmi mein thande lagte; gehre rang zyaada sokhte, isliye gehre kapde sardi mein kaam aate.
Aksar teeno saath hote. Kadaahi mein paani garam karna: lau kadaahi ko chaalan se garam karti, paani poora sanvahan se garam hota, aur kadaahi ke paas garmi vikiran se mehsoos hoti. Bukhari, Himalaya ke gharon ka lohe ka lakdi-chulha, teeno se kamra garam karta aur khaana pakaata.
Explore: chaalan, sanvahan ya vikiran?
- Har ek sort karo.
Yaad rakho
- Vikiran bina maadhyam garmi le jaata; Sooraj ki garmi aise aati.
- Halke rang garmi lautaate, gehre sokhte; aksar teeno prakriyaayein saath.
Quick check
Garmi ka kaunsa tareeka khaali antariksh se kaam karta?
- radiation
- conduction
- convection
- all three
Answer
radiation. Chaalan aur sanvahan ko kan chahiye; vikiran ko nahi.
Socho
Garam jagahon par chhat ki tankiyan aksar safed kyun rangi jaati?
Ek answer
Safed rang Sooraj ka zyaadatar vikiran lautaata, to andar ka paani kam garam hota.
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.