Switches and Resistances

Goal: The goal of this experiment is to understand how current flows through a shunt in a circuit. The voltage drop across the bulb when a part of the current is shunted by turning switch S2 on is reflected by a decrease in the glow of the bulb.
 
Setup: This experiment uses a simple electrical circuit which consists of a bulb, a couple of resistors (R & R1) and two switches (S1 & S2). It is fueled by an emf source of V = 45 V. It is assumed that the internal resistance of the source is negligible.  The value of the resistances are: (R = 10W & R1 = 10W) and the resistance of the bulb is 5W. There are 2 Ammeters which record the current at different points in the circuit, and the Voltmeter, which records the voltage across the points A and B. The participant is expected to experiment with the readings of the voltmeter and the ammeters by clicking on the various combinations of the two switches S1 and S2.

Background: The student should realize that situation when both the switches are on, the bulb glows less than the situation when only switch S1is on. This also coincides with the fact that the value of the current in Ammeter 1 is less when both switches are than when only S1 is on. This is because in the former case there is a voltage drop across the shunt resistance as well as across the bulb. Since they are in parallel, the net potential drop still remains the same, but the current is distributed across each arm. Hence the voltage across the bulb drops, resulting in it glowing less.