$A$ $2 \ V$ cell is connected across points $A$ and $B$ as shown in the figure. Assume that the resistance of each diode is zero in forward bias and infinity in reverse bias. The current supplied by the cell is (in $A$)

Refer to the circuit diagram given in the figure. Which of the following observations are correct?
$A.$ Total resistance of the circuit is $6 \ \Omega$.
$B.$ Current in the ammeter is $1 \ A$.
$C.$ Potential across $AB$ is $4 \ V$.
$D.$ Potential across $CD$ is $4 \ V$.
$E.$ Total resistance of the circuit is $8 \ \Omega$.
Choose the correct answer from the options given below:

In the given figure,which of the diodes are forward biased?

In the following circuit,the equivalent resistance between $A$ and $B$ is

When a semiconducting device is connected in series with a battery and a resistance,a current is found to flow in the circuit. If,however,the polarity of the battery is reversed,practically no current flows in the circuit. The device may be

$A$ thermistor is usually made of......