When switching from a 15 inch to a 19 inch monitor, do the number of horizontal lines change?

The correct understanding revolves around the concept of monitor resolution rather than the physical size of the screen. The number of horizontal lines refers to the resolution of the display rather than its dimensions. When changing from a 15-inch monitor to a 19-inch monitor, the monitor's size increases, but this does not inherently mean that the number of horizontal lines changes unless the resolution specified for the monitors is different.

For example, if both monitors have the same resolution, such as 1024x768 pixels, they will have the same number of horizontal lines regardless of the increase in size. Many displays can have the same resolution but vary in physical size, which would maintain the horizontal lines count. Thus, the number of horizontal lines remains the same when transitioning between these two sizes of monitors when their resolutions are unchanged.