The resistance of platinum wire at 0 is 2 Ω and 6.8 Ω at 80. The temperature coefficient of resistance of the wire is: (a) 3 × 10⁻³ C⁻¹ (b) 3 × 10⁻² C⁻¹ (c) 3 × 10⁻¹⁰ C⁻¹ (d) 3 × 10⁻⁴ C⁻¹

Answer: (b). Rt = R₀(1 + α t) ⇒ α = (Rt - R₀)/(R₀ t) α = (6.8 - 2)/(2 × 80) = (4.8)/(160) α = 0.03 = 3 × 10⁻² ⁻¹ So the answer is (b) 3 × 10⁻² C⁻¹.

The resistance of platinum wire at 0 is 2 Ω and 6.8 Ω at 80. The… | NEET 2023

Q16NEET 2023Easy

Ohm's Law, Resistivity & Temperature

The resistance of platinum wire at $0^\circ\text{C}$ is $2\ \Omega$ and $6.8\ \Omega$ at $80^\circ\text{C}$ . The temperature coefficient of resistance of the wire is:

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Answer: (b)

$R_t = R_0(1 + \alpha t) \Rightarrow \alpha = \dfrac{R_t - R_0}{R_0 t}$
$\alpha = \dfrac{6.8 - 2}{2 \times 80} = \dfrac{4.8}{160}$
$\alpha = 0.03 = 3 \times 10^{-2}\ ^\circ\text{C}^{-1}$
So the answer is (b) $3 \times 10^{-2}\ \text{C}^{-1}$ .

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