What is the effect of a rise in temperature in the resistance of pure metals?*Constant resistanceNoneIncrease resistanceDecrease resistance

Effect of Temperature on Resistance of Pure Metals

When considering the effect of temperature on the resistance of pure metals, it is important to understand the relationship between temperature and resistivity. In general, for pure metals, as the temperature increases, the resistance also increases. This phenomenon is primarily due to the increased energy of the metal ions, which results in more frequent collisions between the charge carriers (typically electrons) and the vibrating metal ions.

1. Increased Temperature: As the temperature of a pure metal rises, the metallic lattice becomes more agitated, leading to increased vibrations.
2. Collision Frequency: This agitation results in a higher frequency of collisions between electrons, which increases the resistance to the flow of electric current.
3. Resistivity Relation: The resistance $R$ can be mathematically described using the formula $R = \rho \frac{L}{A}$, where $\rho$ is the resistivity, $L$ is the length of the conductor, and $A$ is the cross-sectional area. As temperature rises, $\rho$ generally increases for pure metals.

Conclusion

Thus, the correct answer to the question is: Increase resistance.