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please explain your answer A student measures the resistivity of a certain mater

ID: 2112004 • Letter: P

Question



please explain your answer

A student measures the resistivity of a certain material at three different temperatures and gets the results summarized in the following table. Temperature Resistivity 20° C po 32.500 x 10 52. m X 10-8 O. m TI 0° C T2 -100 C p2 3.036 x 10 2. m If an equation of the form po (1 a(T- o) B (T -To)2) with To 20 C, is used to fit the data, determine a and B (a) a 1.0 x 10 31/(OC), B 6.0 x 10-61/(oC)2 (b) a 2.0 x 10-3 1/(OC), 8 5.0 x 10-61/(OC)2 (c) a 3.0 x 10 31/(OC), 8 4.0 x 10-61/(oC)2 (d) a 4.0 x 10 31/(OC), B 3.0 x 10 61/(oC)2 (e) a 5.0 x 10 31/(OC), 8 2.0 x 10-61/(oC)2 (f) None of the above.

Explanation / Answer

since for T1= 0 rho1= 2.346 x 10^-8 and for T2= 100 ,eho2 = 3.036 x 10^-8

we get option (c) alpha = +3 x 10^-3 and beta = -4 x 10^-6

super conductor is which the resistance drops abruptly to 0

substituting the values of alpha and beta we get a quadratic equation in (T - T0)

solving which gives the value of (T-T0) as -250 and T0 =20

=> T= -230 i.e option (b)