UPSC Darpan

PhysicsPushan · Class 9-10

mgh se bijli tak: hydropower ki energy chain

Ek plant 10 metre ki oonchai se paani girata hai aur doosra 100 metre se. Paani utna hi ho, toh kiski bijli zyada?

Socho pehle… phir dekho jawab

100 metre wale ki. Potential energy = mgh; oonchai (h) das guna, toh girte paani ki energy bhi das guna. Isliye engineers 'head' (paani ki girne wali oonchai) badhane ke liye baandh banate hain.

Energy conservation: baandh ke upar paani ki potential energy (mgh) girte waqt kinetic energy (½mv²) mein badalti hai. Turbine is kinetic energy ko ghoomne (mechanical energy) mein, aur generator mechanical ko electrical mein badalta hai. Har step par thodi energy ghisaav aur garmi mein chali jaati hai, isliye poori mgh bijli nahi banti.

Power = energy per second. Isliye do cheezein matter karti hain: head (h) aur har second bahne wala paani. Example (sirf samajhne ke liye): har second 1,000 kg paani (1 m³) 100 m gire, toh mgh = 1000 × 9.8 × 100 ≈ 10 lakh joule har second, yaani lagbhag 1 MW. Ab socho, 1,605 MW ke liye kitna paani aur kitna head chahiye!

So what: hydropower renewable hai, bijli banate waqt dhuaan nahi, aur yeh 'firm' bijli deta hai jo solar aur wind ke utaar-chadhaav ko balance kar sake. Storage dam baadh ke paani ko rok kar baadh-niyantran bhi karta hai.

Ghar pe try karo

Calculator se table banao: m = 1,000 kg har second, g = 9.8 m/s². h = 10, 50, 100 aur 237 m ke liye mgh nikalo (watt mein). Phir maano (sirf example) plant 90% energy ko bijli bana paata hai — har row mein kitni bijli bachi?

Wow!

Sirf 1 m³ paani har second 100 m se gire toh (loss chhod kar) lagbhag 1 MW — itne mein 10 watt ke lagbhag 1 lakh LED bulb jal sakte hain!

3 sawaal

  1. Head (h) doguna ho aur paani utna hi, toh girte paani ki energy?
    Jawab dekho

    Doguni. PE = mgh; h doguna toh energy doguni.

  2. Hydropower mein generator kaunsa badlaav karta hai?
    Jawab dekho

    Mechanical se electrical. Turbine ka ghoomna (mechanical) generator mein bijli (electrical) banta hai.

  3. Poori mgh bijli kyun nahi banti?
    Jawab dekho

    Har step par kuch energy ghisaav aur garmi mein jaati hai. Energy khatam nahi hoti, par kuch hissa ghisaav aur garmi ban jaata hai.

NCERT se jodo: NCERT Class 9 Science — work and energy (potential aur kinetic energy, energy conservation)

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