In the given diagram all are NOR Gate . The final output is shown in the figure. At stage 1 the output will be \overline A \& \overline B At stage 2 the output will be \overline {\overline A + \overline B } = A.B And the final output will be \overline {A.B} Hence for input A & B the output is \overline {AB} in case of Nand gate.
Constantin‘, also known as ‘Eureka wire‘, is the trade-name for a copper-nickel alloy (approx. 60:40 ratio) formulated in the late 1800s by Edward Weston.