Garmi aur Bijli ka Chaalan

Class 7 Science · Chapter 4: Dhaatu aur Adhaatu ki Duniya · NCERT Curiosity section 4.1.4–4.1.5

Seekho

Ishaan ek jitne steel aur lakdi ke chammach garam paani ke gilaas mein rakhta hai. Kuch minute baad steel ka chammach upar se garam, lakdi wala mushkil se gungunaa. Garmi dhaatu mein chalti hai: ye chaalan (conduction) hai, aur garmi aage badhaane wale padaarth chaalak hain.

Dhaatuein garmi ki achchhi chaalak; lakdi aur plastic kharaab. Isiliye bartan dhaatu ke hote hain par hatthe lakdi ya plastic ke: bartan khaana garam karta, hattha pakadne layak thanda. Garmi ke behne ko aage garmi wale chapter mein dekhenge.

Bijli wale chapter ke tester circuit se aluminium foil, lohe ki keel aur taambe ka taar bulb jalaate hain; gandhak, koyla, lakdi, patthar, rubber aur nylon nahi. Bijli chalaane wale saare padaarth dhaatu hain. Kharaab chaalak hamein surakshit rakhte: pechkas ke hatthe plastic ke aur bijli mistri rubber ke dastaane pehente hain.

Dhaatuon ka saar: aam taur par sakht, chamakdaar, malleable, ductile, sonorous, aur garmi aur bijli ki achchhi chaalak. Paani ubaalne ke bartan ke liye kaunsi? Achchhi garmi-chaalak jo na pighle na jale, jaise taamba, aluminium ya loha, gandhak, koyla, plastic ya lakdi nahi.

Explore: chaalak ya nahi?

1. Har cheez tester se jaanchkar sort karo.

Yaad rakho

• Dhaatuein garmi aur bijli achchhi chalaati; gandhak, koyla jaise adhaatu nahi.
• Kharaab chaalak suraksha ke liye hatthe, dastaane aur taar ke aavaran banaate.

Quick check

Bartanon ke hatthe lakdi ke kyun?

1. lakdi garmi ki kharaab chaalak
2. lakdi garmi achchhi chalaati
3. lakdi dhaatu
4. lakdi chamakdaar

Socho

Paani ubaalne ke liye taambe ke bartan. Kya isliye ki taamba bijli achchhi chalaata hai?

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.