P-V diagram for isothermal process · CAP 2013 #17
Physics · thermodynamics
Problem
Which of the accompanying P−V diagrams best represents an isothermal process, that is a process occurring at constant temperature? [Figure: Five P-V diagrams labeled a) through e) showing different curves and lines]Intuitive explanation
An isothermal process keeps temperature constant, which means the product must stay constant (from the ideal gas law). On a P-V diagram, this relationship traces a hyperbola—a curve that bends smoothly downward as volume increases and pressure decreases. Look for the graph that shows this characteristic curved path rather than a straight line, since straight paths represent processes where temperature is changing.
Intuitive explanation
An isothermal process keeps temperature constant, which means the product must stay constant (from the ideal gas law). On a P-V diagram, this relationship traces a hyperbola—a curve that bends smoothly downward as volume increases and pressure decreases. Look for the graph that shows this characteristic curved path rather than a straight line, since straight paths represent processes where temperature is changing.