Read the below case and answer the following questions:
During a science practical, Ananya and her classmates were asked to build a simple electrical circuit using two electric cells, a cell holder, connecting wires, and an LED. They first removed a small portion of the plastic covering from both ends of the connecting wires to expose the metal. Then, they connected the wires to the cell holder and inserted the two cells carefully, ensuring that the negative terminal of each cell faced the spring side of the holder.
Next, Ananya connected the longer lead of the LED to one wire from the battery and the shorter lead to the other wire. The LED glowed brightly. Curious to know more, she interchanged the two connections of the LED without changing any other part of the circuit. This time, the LED did not glow. Their teacher explained that an LED works only when it is connected with the correct polarity. The activity also helped the students understand the importance of a closed circuit, battery polarity, and the difference between Direct Current (DC) supplied by cells and the behaviour of an LED.
Next, Ananya connected the longer lead of the LED to one wire from the battery and the shorter lead to the other wire. The LED glowed brightly. Curious to know more, she interchanged the two connections of the LED without changing any other part of the circuit. This time, the LED did not glow. Their teacher explained that an LED works only when it is connected with the correct polarity. The activity also helped the students understand the importance of a closed circuit, battery polarity, and the difference between Direct Current (DC) supplied by cells and the behaviour of an LED.
1. Why were both cells placed with their negative terminals towards the spring side of the cell holder?
2. Why did the LED glow only when its longer lead was connected correctly?
3. Which type of current was supplied by the two electric cells used in the activity?
4. What was the main learning outcome of Ananya's experiment?