Objective: You will observe brightness of bulbs in series and parallel circuits. Apparatus: Electrical circuit kit, ammeter, voltmeter, light bulb, battery. Go to http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc Background Theory: A series circuit is a loop of wire in which circuit loads are connected in series. Therefore, there is only one electric current passing through the circuit. A parallel circuit has more than one loop of wire in which circuit loads are connected in parallel. Therefore, different electric current may flow through different loads. What will happen to brightness of light bulbs if they are in series and parallel circuits? Experimental Method: A Qualitative Part Construct a simple circuit with a battery and light bulb with some wires and observe brightness of light bulb. Bulbs need to be placed inside of socket which should be connected with wires. Construct a series circuit with 2 light bulbs and a battery and observe brightness of lightbulbs. Take one bulb out, what happens to the other bulb? Construct a parallel circuit with 2 light bulbs and one battery and observe brightness of lightbulbs. Take out one bulb, what happens to the other bulb? Which circuit displayed a brighter light bulb? Why? Repeat step2 with two batteries instead of one battery. What is the difference now? Why? Repeat step2 with three batteries instead of one battery. What is the difference now? Why? B Quantitative Part 1 Construct a simple circuit with a battery and light bulb with some wires. Measure current in the circuit and voltage across battery and light bulb. 2. Construct a series circuit with 2 light bulbs and two batteries. Measure the voltage across two batteries and each light bulb. What is the relationship between the voltage of two batteries and light bulbs? With an ammeter, measure current in the wire next to the batteries. Do you expect the current to be the same between the light bulbs? What is your prediction? Measure the current in between the light bulbs. Replace light with 1Oohm resistors and repeat the same process 3 Construct a parallel circuit with 2 light bulbs and two batteries. Measure the voltage across two batteries and each light bulb. What is the relationship between the voltage across two batteries and light bulbs? Measure current through a wire next to the batteries first. Then measure current through one light bulb. What is your prediction for current passing through the other light bulb? Replace light with 1Oohms resistors and repeat the same process.

A Qualitative Part

Steps Observation I.simple circuit 2a.series circuit, two bulbs 2b.parallel circuit, two bulbs 3a.series circuit, two bulbs, two batteries 3b.parallel circuit, two bulbs, two batteries 4a.series circuit, two bulbs, three batteries 4b.parallel circuit, two bulbs, three batteries

B Quantitative Part

Steps observation 1 simple circuit Current= V (battery V (bulb 2 series circuit

Light bulbs

10 ohms resistors V(batteries)= V (bulbI)= V(bulb2)= Current next to batteries= Current between bulbs prediction= Current between bulbs measured=

V(batteries)= V (RI)= V(R2)= Current next to batteries= Current between resistors prediction= Current between resistors measured= 3 Parallel circuit

Light bulbs

IO ohms resistors V(batteries)= V (bulbI)= V(bulb2)= Current next to batteries= Current between bulbs prediction= Current between bulbs measured=

V(batteries)= V (RI)= V(R2)= Current next to batteries= Current through resistor I measure= Current through resistor2 predicted= Current through resistor2 measured=

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