In a transistor amplifier, a change of 0.2 mA in the base current causes a change of 5 mA in the collector current. If input resistance is $2\ \text{k}\Omega$ and voltage gain is 75, the load resistance used in the circuit is

The resultant gate and its Boolean expression in the given circuit is

When a small amount of impurity atoms are added to a semiconductor then generally its resistivity

In the logic circuit diagram, when all the four inputs, A, B, C, D are 'one' the outputs $Y_1$, $Y_2$, $Y_3$ are respectively (1, 1, 0). When the inputs A and C are changed to zero and B and D are still 'one', then the outputs $Y_1$, $Y_2$, $Y_3$ are respectively change to