α is the temperature coefficient of a material represented as :  α = \(\frac{R - R_{o}}{θR_{o}}\) Which of the following is true about the temperature coefficient?

It is always a negative quantity. It is negative only for metals. It is positive for semiconductors and insulators. None of the above.

None of the above.

Temperature coefficient can be negative or positive. It is positive for metals. It is negative for insulators and semiconductors.