Temperature dependence of conduction: If a material’s conductance increases as temperature increases, this behavior is known as having a:

Introduction / Context:
Materials respond to temperature in different ways. Metals typically become more resistive when heated, while many semiconductors and certain composites conduct better as temperature rises. Understanding the sign of the temperature coefficient helps in sensor design (thermistors), compensation networks, and predicting circuit behavior over environmental ranges.

Given Data / Assumptions:

• We are told conductance increases with temperature.
• Conductance G is the reciprocal of resistance R (G = 1 / R).
• Standard engineering terminology for ”temperature coefficient” is used.

Concept / Approach:
If conductance increases with temperature, then resistance decreases with temperature. A decrease in resistance as temperature increases corresponds to a negative temperature coefficient (NTC). Many semiconductors and thermistor devices exhibit this NTC behavior, which is exploited for inrush limiting and temperature sensing.

Step-by-Step Solution:

Verification / Alternative check:
Thermistors labeled NTC clearly show larger G (smaller R) as they warm. In contrast, metals generally have a positive temperature coefficient (PTC), where G decreases (R increases) with temperature. The problem statement matches NTC behavior, hence ”negative coefficient.”

Why Other Options Are Wrong:

• Positive coefficient: Opposite trend (resistance would rise with temperature).
• Negative current flow: Nonsensical in this context; current direction can be defined by reference, not temperature.
• Positive resistance: Nearly all passive materials have positive resistance; this does not describe temperature dependence.

Common Pitfalls:
Mixing up conductance and resistance; always remember G = 1 / R. Also, ”coefficient” refers to the sign of dR/dT (or dG/dT), not a qualitative statement about current direction.

Final Answer:
negative coefficient