Basic Physics II Evidences - DrJJ - UiTM

Material SciencePHY4077. What happens to the brightness of the first bulb, the voltage across it and thecurrent in the circuit when a third bulb is added in series to the circuit?8. Can you propose a model on how the brightness of the bulbs change as thenumber of bulbs are increased or decreased in a series circuit?9. Is there a relationship between the number of bulbs and the current in acircuit?10. How can this brightness model be related to the electrical power?11. What happens to the current in the circuit when any one of the bulbs isunscrewed? Explain.Investigation 2 - Bulbs in ParallelPrediction 2.1: (The battery shown in the figure below is a 1.5 V battery)i) Will all the bulbs in the parallel circuit have the same brightness?ii) What will the voltmeter reading be if the probes are connected between pointsA and B and between C and D respectively for the bulbs connected iniii)parallel?S 1Would the BADFHchange if thevoltage readingS 2S 3S 4probes areplaced across theterminals of theR 1R 2R 3second bulb(between E andF), and acrossthe terminals ofthe third bulb A(between G andH)?CEGiv) Would you consider the contact points at point B, D, F and point H to be anequipotential point?v) Will the current going through the circuit the same as the current through thefirst bulb, the second bulb or the third bulb?vi) What will happen to the brightness if one bulb is unscrewed, if 2 bulbs areunscrewed? What happens to the current in the circuit?Battery 1.5 VA1A2A3Activity 2.1: (You MUST run the PhET (Circuit Construction Kit (DC only)) simulation firstbefore attempting to do the following activities in the lab. Set the batteryvoltage to 1.5 V and the resistance for each bulb at 1.0 Ω)i) Connect the bulbs in parallel as shown in the figure but start with 2 bulbsfollowed by three bulbs. Observe the brightness of the bulbs as more bulbsare added in parallel. Then, using a multimeter with the dial set on DC mode,measure the voltage across the battery, V AB , the voltage across the first bulb,V CD , the voltage across the second bulb, V EF , and the voltage across the thirdbulb, V GH . Record your reading.Created by Dr. JJ, FSG, UiTM Shah Alam Page 5 of 7 3/3/2010