-Several numbers are considered significant in a measurements. Non-zero digits are always significant. Thus, 569 has three significant digits, and 69.35 has four significant digits.
-Zeros are sometimes significant and sometimes aren't:. Zeroes placed before other digits are not significant; 0.0968 has three significant digits.
-Zeros placed between other digits are always significant; 70063 kg has five significant digits. Zeros placed after other digits but behind a decimal point are significant; 7.90 has three significant digits. Zeros at the end of a number are significant only if they are behind a decimal point.
Reflection involves a change in direction of waves when they bounce off a barrier. Refraction of waves involves a change in the direction of waves as they pass from one medium to another.
