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Assertion (A) : The temperature dependence of resistance is usually given as: R = R0(1+αΔT).The resistance of a wire changes from 100Ω to 150Ω, when its temperature is increased form 27℃ to 227℃. This implies that α = 2.5 × 10−3℃−1.Reason(R) : R = R0(1+αΔT) is valid only when the change in temperature ΔT is small and ΔR = (R − R0 ) << R0.(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false and R is also false |
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Answer» Option : (C) Given that, R –R0 = R0∝ ∆ 150-100 = 100×∝× (227 − 27) ∴ \(\frac{50}{100}\) =∝× 200 Or, ∝ = 2.5 × 10−3℃−1 Therefore, Assertion is true. Reason is false as R – R0 = 150 – 100 = 50Ω, Which is not much-much less than R0 (= 100Ω). |
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