The circuit is equivalent to: 
     

1. AND gate
2. NAND gate
3. NOR gate
4. OR gate

In the following circuit, the output \(Y\) for all possible inputs \(A\) and \(B\) is expressed by the truth table: 
    

The figure shows a logic circuit with two inputs \(A\) and \(B\) and the output \(C\). The voltage waveforms across \(A\), \(B\), and \(C\) are as given. The logic circuit gate is:
         

1. \(\text{OR}\) gate
2. \(\text{NOR}\) gate
3. \(\text{AND}\) gate
4. \(\text{NAND}\) gate

The zener breakdown will occur if:

The logic behind the 'NOR' gate is that it gives:

In a transistor circuit shown here, the base current is  35 $\mathrm{\mu }$A  and the potential difference across emitter-base junction is 4.5 V. The value of the resistor R_b is:
                 

1. 128.5 k$\mathrm{\Omega }$

2. 257 k$\mathrm{\Omega }$

3. 380.05 k$\mathrm{\Omega }$

4. None of these

In a transistor, a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current?
1. 50 $\mathrm{\mu }$A 
2. 100 $\mathrm{\mu }$A
3. 150 $\mathrm{\mu }$A 
4. 200 $\mathrm{\mu }$A

An NPN transistor conducts when: