Electronics Questions

When an npn transistor is used as an amplifier:

For a transistor amplifier in common emitter configuration having load impedance of $1\text{k}\Omega$ ($h_{fe}=50$ and $h_{oe}=25\times 10^{-6}\text{A/V}$), the current gain is:

A piece of copper and another of germanium are cooled from room temperature to $77\text{K}$. The resistance of:

The manifestation of band structure in solids is due to:

When a p-n junction diode is forward biased:

In a common base amplifier, the phase difference between the input signal voltage and output voltage is:

In a full wave rectifier circuit operating from $50\text{ Hz}$ mains frequency, the fundamental frequency in the ripple would be:

A working transistor with legs marked P, Q and R is tested. No conduction is found between P and Q. Connecting the negative terminal of the multimeter to R and positive to P or Q shows some resistance. Which is true?

A circuit has two inputs A and B and output C. The truth table shows C is 0 only when both A and B are 0, and C is 1 otherwise. This circuit represents:

A logic gate circuit has two inputs $A$ and $B$. Both are passed through NOT gates, then through a NAND gate, and finally through another NOT gate. This combination yields: