The resistance of the wire made of silver at \(27^{\circ} \mathrm{C}\) temperature is equal to \(2.1 \Omega\) while at \(100^{\circ} \mathrm{C}\) it is \(2.7 \Omega\) calculate the temperature coefficient of the resistivity of silver. Take the reference temperature equal to \(20^{\circ} \mathrm{C}\) (A) \(4.02 \times 10^{-3}{ }^{\circ} \mathrm{C}^{-1}\) (B) \(0.402 \times 10^{-3}{ }^{\circ} \mathrm{C}^{-1}\) (C) \(40.2 \times 10^{-4}{ }^{\circ} \mathrm{C}^{-1}\) (D) \(4.02 \times 10^{-4}{ }^{\circ} \mathrm{C}^{-1}\)

Short Answer

Expert verified
The temperature coefficient of resistivity of silver is approximately \(4.02 \times 10^{-3}{ }^{\circ} \mathrm{C}^{-1}\).

Step by step solution

01

List the given information

We are provided with the following values: - Resistance at \(27^{\circ}\mathrm{C}\): \(R_{27} = 2.1 \Omega\) - Resistance at \(100^{\circ}\mathrm{C}\): \(R_{100} = 2.7 \Omega\) - Reference temperature: \(t_0 = 20^{\circ}\mathrm{C}\)
02

Set up two equations using the resistance formula

We can set up two equations using the temperature coefficient of resistivity formula: - Equation 1: \(R_{27} = R_0[1 + \alpha (27 - 20)]\) - Equation 2: \(R_{100} = R_0[1 + \alpha (100 - 20)]\)
03

Solve for R_0 using Equation 1

Using Equation 1, we can solve for the reference resistance \(R_0\): \(2.1 = R_0[1 + \alpha (7)]\)
04

Substitute R_0 from Equation 1 into Equation 2

Now we substitute the expression for \(R_0\) from Step 3 into Equation 2: \(2.7 = \frac{2.1}{1 + 7\alpha}[1 + 80\alpha]\)
05

Solve for alpha

Now, we need to solve the equation for \(\alpha\): \(\frac{2.7}{1 + 80\alpha} = \frac{2.1}{1 + 7\alpha}\) Cross-multiplying, we get: \(2.7 (1 + 7\alpha) = 2.1 (1 + 80\alpha)\) Expanding both sides: \(2.7 + 18.9\alpha = 2.1 + 168\alpha\) Now we can isolate \(\alpha\): \(150.9\alpha = 0.6\) \(\alpha = \frac{0.6}{150.9}\)
06

Calculate the value of alpha and choose the correct option

Now, we can calculate the value of \(\alpha\): \(\alpha \approx 0.00402^{\circ}\mathrm{C}^{-1}\) Now, we can see that the correct option is: (A) \(4.02 \times 10^{-3}{ }^{\circ} \mathrm{C}^{-1}\)

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