The element D1 in the transmitter is a light-emitting diode (LED). An LED is an element that emits light and whose brightness is controlled by the current flowing through it. You can recall controlling the light emitted by an LED in various labs during the course. In our circuit, the current through the LED, hence its brightness, can be controlled by choosing the applied voltage Vin and the value of the resistor R. The light from the element D1 in the transmitter is received by the element D2 in the receiver. In this circuit, the LED D1 is used as a means for transmitting information with light, and the element D2 is used as a light receiver to see if anything was transmitted. In the receiver, the element labeled as D2 behaves like a "reverse biased" solar cell, which means that when it receives light, it generates a current. We will denote the current generated by the solar cell by IS. Remark: Non-idealities, such as background light, affect the performance of a system that does light mea- surements. In this question, we will assume ideal conditions, that is, there is