General Physics 2 Lab - PHY 2049L Lab 8: AC Circuits – Circuits PhET Lab Name __________________________ Date __________________________ Simulation: Play with Simulations: Simulation: Circuit Construction Kit (AC+DC) http://phet.colorado.edu/en/simulation/circuit-construction-kit-ac (Background: Tipler, Chapter 30-8. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/induct.html#c1) Circuits PhET Lab Introduction: Wouldn’t it be great to see inside wires and electrical devices, to actually watch the electrons flow? This simulation allows us to do this. In this sim, you will build simple and compound circuits and measure their potential (voltage), current, and resistance. Additionally, you will view the actions of electrons in an AC circuit. Important Formulas: Series: Parallel: Procedure: PheT Sims Play Electricity, Magnets, and Circuits Circuit Construction Kit (AC+DC) • • • • • To add elements to your circuits, simply drag an item into the work area. To remove an item or change it, right-click the item you wish to change. To uncouple two circuit elements, right click on the circular junction and choose “split junction.” To measure voltage and current, click on the boxes to the left. Remember, voltage is read in parallel (outside of the circuit), while current is read in series (in the circuit) Directions 1. Construct the circuit shown below. V= 5 V (Volt) R1 = 5 Ω (Ohm) C= 0.02 F (Farad) L= 0.1 H (Henry) 2. If a capacitor, C, stores a charge, Q, the capacitor’s electric field stores an energy given by the equation. UE = ½ Q 2/ C 3. If an inductor, L, carries a current, I, the inductor’s magnetic field stores an energy given by the equation. UB = ½ L I2 4. Close switch S1 and open switch S2. Once the capacitor is fully charged open switch S1 and close switch S2. Observe the periodic charging and discharging of the capacitor and inductor. 5. Graph and identify the energy stored in the capacitor and inductor for one period on the axis below. Place a voltage chart across the capacitor and a current chart in line with the inductor. UE − MAX or MIN UB − MAX or MIN UE − MAX or MIN UB − MAX or MIN UE − MAX or MIN UB − MAX or MIN UE − MAX or MIN UB − MAX or MIN UE − MAX or MIN UB − MAX or MIN 6. Draw a curve representing the total energy of the LC system. 7. Insert a light bulb for R2. V= 20 V R1 = 5 Ω (Ohm) R2 = 0.85 Ω (Ohm) C= 0.02 F L= 0.1 H 8. Recharge the capacitor, see step 4, and observe the periodic charging and discharging of the capacitor and inductor. 9. Does . If no, what does it equal? Pre-Lab Quiz: Alternating Current circuits differ from Direct Current circuits in that the direction of their current changes sixty times each second (60Hz). In the classroom, the lights are actually turning on and off 60 times each second, much faster than our eyes can see, so the lights appear to be constantly on. The simulation slows down the current so we can observe the current. • Build a series circuit. Observe the flow of electrons in an AC circuit. • Describe the actions of the electrons in your AC circuit. _________________________________________________ • Can an AC circuit be shorted just like a DC circuit? _____________________________________________________ • Build a parallel circuit using an AC power source. • Are all the lights in a parallel AC circuit the same brightness? _____________________________________________ • Click on the and observe the graph of current vs time. Draw the graph.