We know that a statement in logic is either true or false. The same situation occurs in electric switches. A working switch is either on (closed) or off (open). If a switch is ‘on’ it allowed electric current to pass the circuit and lamp glows and if the switch is ‘open’ it does not allow current to pass the circuit and lamp does not glow. We shall denote ‘on’ switches by letters S, , , ,… and open switches are denoted by letters S’, , ,…But the symbol is used to denote both the switches are the same only differ by the letters S and S’. Let the statement p denote the ‘switch S is closed’ and lamp with light by l. Then its symbolic form is p l. Let ~p: the switch S’ is closed and lamp with no light by l’ Then its symbolic form is ~p l’. Switches connected in the circuit in two different ways 1. In series 2. In parallel. 1. Switches connected in series Add ca...