Video narration
Jab torch ki batteries kamzor ho jati hain, to uski roshni dheemi kyon pad jati hai? Torch ke bulb ki chamak is baat par nirbhar karti hai ki usmein kitna current - vidyut aavesh ka pravaah - bah raha hai. Current zyada, chamak zyada; kam, to kam. Ohm's law, yani Ohm ka niyam, voltage, current aur resistance ka sambandh batata hai. Voltage current ko chalane wala electrical push hai, jabki resistance uske pravaah ka virodh hai. Sutra hai: V = I x R. Yahin rahasya khatm hota hai: resistance vahi rahe, to voltage ghatne par current bhi ghatta hai. Kamzor battery kam voltage deti hai, isliye usi bulb mein kam current bahta hai. Saral model mein resistance sthir maante hain; asli incandescent bulb garam hokar badalta hai, isliye Ohm's law har component par poori tarah lagu nahin hota. Phir bhi torch ka jawab hai: battery ka voltage kam hua, current ghata, aur isi vajah se brightness kam ho gayi.