None. The speed of light is usually assumed to be constant. The symbol used to represent the speed of light is "C", as in E=MC2. Then why is it called a variable speed?
Variable: A letter or symbol used to represent a number or quantities that vary
any number at all
a variable
a is used as a symbol to represent a variable.
variable
c
Variable: A letter or symbol used to represent a number or quantities that vary
#
a variable
any number at all
A letter used to represent a number is called a variable. Typically, the letters x and y are used, but technically you can use any letter of the alphabet.
It is a variable
A variable
variable
Variable
Variable
a variable