$A$ thermoelectric refrigerator works on

The voltage gains of two amplifiers connected in series are $8$ and $12.5$. If the voltage of the input signal is $200 \mu V$, then the voltage of the output signal is

Three amplifiers with voltage gains $10, 20$ and $30$ are connected in series. If the input signal has a peak value of $1 mV$, then the peak value of the output voltage is (in $\,V$)

In an oscillator,for sustained oscillations,the Barkhausen criterion is $A \beta$ equal to (where $A =$ voltage gain without feedback,$\beta =$ feedback factor).

$Ge$ and $Si$ diodes conduct at $0.3 \, V$ and $0.7 \, V$ respectively. In the following figure,if the $Ge$ diode connection is reversed,the value of $V_0$ changes by how many volts?

In the circuit given below, $V(t)$ is the sinusoidal voltage source. The voltage drop $V_{AB}(t)$ across the resistance $R$ is: