In general use, a lowercase 'b' represents the unit bit (56 kbps = 56 kilobits per second)
This is not to be confused with an uppercase 'B' which, in a similar context, represents the unit 'Byte' (a Byte is made up of eight bits).
The bit is not defined in the International System of Units (SI), The International Electrotechnical Commission standard IEC 60027 gives the symbol for a binary digit as bit(including kbit, mbit etc), and the lower-case letter b was recommended by the IEEE 1541 Standard (2002).
In the symbol AB, the letter A represents the starting point or origin of the line segment.
variable
A variable.
a variable
The unit that measures Capacitance is Farads. The letter symbol for that is a capital F.
Not necessarily. A represents anything which you define it to be.
veribal
The letter in chemistry that represents heat is the letter Q. Q is the heat of the reaction that has occurred.
The atomic symbol in a Lewis structure represents the nucleus of an atom, typically denoted by a letter. It does not include any electrons. The letter serves to identify the element that the atom represents.
a letter.
The letter E represents the note Mi.
A letter is a symbol that represents a sound or idea in written language.