1.	It is a \(V\text-I\) characteristic of a solar cell where the point \(A\) represents open-circuit voltage and the point \(B\) represents short-circuit current.
2.	It is for a solar cell and points \(A\) and \(B\) represents open-circuit voltage and current respectively.
3.	It is for a photodiode and points \(A\) and \(B\) represents open-circuit voltage and current respectively.
4.	It is for an LED and points \(A\) and \(B\) represents open-circuit voltage and short-circuit current respectively.

1.	\(\mathrm{n}\text-\)type with electron concentration \(n_{e}=5\times10^{22}~\text{m}^{-3}\)
2.	\(\mathrm{p}\text-\)type with electron concentration \(n_{e}=2.5\times10^{23}~\text{m}^{-3}\)
3.	\(\mathrm{n}\text-\)type with electron concentration \(n_{e}=2.5\times10^{10}~\text{m}^{-3}\)
4.	\(\mathrm{p}\text-\)type with electron concentration \(n_{e}=5\times10^{9}~\text{m}^{-3}\)

1.	the current in the reverse biased condition is generally very small.
2.	the current in the reverse biased condition is small but the forward-biased current is independent of the bias voltage.
3.	the reverse-biased current is strongly dependent on the applied bias voltage.
4.	the forward-biased current is very small in comparison to reverse-biased current.

1.	\(10^{17} / \text{m}^3 \)	2.	\(10^{15} / \text{m}^3 \)
3.	\(10^4 / \text{m}^3 \)	4.	\(10^2 / \text{m}^3\)