Working principle of the raster scan

Question

Describe the working principle of the raster scan.

Answer 1

Beginning from the top left corner of the screen, the electron gun scans (or sweeps) horizontally from left to right, one scan line which is one row at a time, jumping (devoid of tracing the line) to the left end of the next lower row till the bottom right corner is reached. Then it jumps (again devoid of tracing) to the top left corner and begins again, completing one complete refresh cycle.

The chief demerit of the raster scan is the jagged nature of lines, occurring from the fact that the pixels are aligned all along regular rows and columns and points on line will not, in general drop on the exact centre of pixels.