question_answer

The resistance\[{{R}_{t}}\] of a conductor varies with temperature t as shown in the figure. If the variation is represented by \[{{R}_{t}}={{R}_{0}}[1+\alpha t+\beta {{t}^{2}}]\], then                                     [CPMT 1988]

A)            \[\alpha \] and \[\beta \] are both negative

B)            \[\alpha \] and \[\beta \] are both positive

C)            \[\alpha \] is positive and \[\beta \] is negative

D)            \[\alpha \] is negative and \[\beta \] are positive

Correct Answer: B

Solution :

                   Since the value of R continuously increases, both a and b must be positive. Actually the components of the given equation are as follows It a is positive, b is negative, the component will be shown in the following graph. In this case, the value of R will not increase continuously. Hence the correct option is .