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The temperature coefficient of a carbon resistor is 5x 10C if the resistance of a carbon resistor is 500 ohm at 0°C, find its resistance at 120°C |
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Answer» ture coefficient of resistance, α=5×10 −3 / ∘ CInitial temperature, T 0 =20 ∘ Initial resistance at T 0 , R 0 =10ΩInitial current at T 0 , I 0 =30mAIncreased temperature, T 1 =120 ∘ INCREASED resistance is,R 1 =R 0 [1+α(T 1 −T 0 )]R 1 =10[1+5×10 −3 (120−20)]R 1 =10[1+5×10 −1 ]R 1 =10[1+0.5]R 1 =10[1.5]=15ΩSince, potential difference ACROSS the ends of wire is constant,V=I 0 R 0 =I 1 R 1 ⇒I 1 = R 1 I 0 R 0 ∴I 1 = 15(30)(10) ∴I 1 = 15300 =20 mA |
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