Key Concepts. 1  The electrons on the outermost energy level of the atom are called valence electrons. 2  The valence electrons are involved in bonding one atom to another. 3  The attraction of each atomâs nucleus for the valence electrons of the other atom pulls the atoms together.
NTSC is the format used in the United States and Canada. NTSC stands for National Television Standard Committee which established the American TV broadcast TV standard as a 525 line broadcast. The NTSC system has higher frame rate (60 Hz) which reduces visible flicker and picture noise.
Other differences are found in the resolution and frequency of the signal. NTSC uses 525 scan lines, of which 486 are visible. NTSC also uses 29.97 interlaced FPS or frames per second, this is done on a signal with frequency of ~60Hz. PAL on the other hand does not set exact format for these things in its specifications, although it uses a pretty standard format. PAL most commonly has 625 scan lines, of which 576 are visible.