Current

“Battery-Resistor”:

Check “show battery” and “show cores”, watch what happens, adjust some variables

1. Why do electrons (blue dots) move? Draw a diagram of the battery, label the flow of electrons. The flow of current (+) is opposite; draw this and note if toward or away from + terminal of the battery.

The electrons are moving because of the voltage of the battery. The current flows in the opposite direction of the electrons and the flow of the electrons is towards the positive side of the battery.

2. What does the Ammeter (on the left) measure? How is this shown in the sim?

The ammeter measures amperes. It is shown in the bottom left of the simulator.

3. What role do the “green dots” in the resistor play in the sim? What do you think they represent? What does this tell you about the effect of resistors in a circuit?

The green dots control the electrons flow in the simulator; in other words, the green dots are putting resistance on the electrons flow. When the resistance (green dots) is turned down, the electrons move faster, and the battery gets hotter.

4. Increase the resistance (# green dots). What affect does this have on temperature? WHY?

It gets colder. Because the electrons are flowing slower, therefore, in a less quantity per second.

5. When the circuit gets hotter, what affect does this have on current? Explain using kinetic-molecular theory.

When the circuit gets hotter, it makes the current increase because of the rapid mobility of electrons flowing.

6. To make the circuit “cold”, what do you need to do? WHY?

To make it colder we need to decrease the voltage, as close to 0 as possible. Because the electrons flow will decrease, making it colder.

7. Describe the relationship between voltage and temperature.

The higher the voltage, the hotter the temperature.

Go to: http://phet.colorado.edu/en/simulation/resistance-in-a-wire.

“Resistance in a Wire”:

1. In this sim, what variables are you seeing? Write the formula below, and indicate the units used to measure each one.

Variables: Resistance, resistivity, length and area.

Formula: R = pL/A

Resistance: ohm. Resistivity: ohm*cm. Length: cm. Area: cm^2

2. Try increasing the resistivity of the resistor, r. How does this change the “look” of the resistor? Describe how that relates to the formula you just wrote (direct, indirect relationships, etc.). What happens to the value of “R” (Resistance)? Is this something that can be changed in a resistor that you would buy in a store to use in a circuit?

Increasing the resistivity increases the number of black dots in the resistor. It relates directly to the formula, the bigger the resistivity, bigger will be the resistance. The value of ‘R” gets bigger. The only thing that I can think to change is the resistance.

3.