FarleyPhysics.com

Do all these questions in an Open Office document.  Don’t cut and paste the answers.  Write the answers in your own words.

Go to this link and find out about vacuum tubes.

1. Explain what Flemming’s first tube did.

2. What did Lee De Forest’s vacuum tube do?

3. Put a picture of a vacuum tube in your document.  You can drag the image to the desktop and then into the document.

4. What kind of devices used vacuum tubes

Go here to learn about transistors.

1. What do transistors do?

2. Finish this sentence: A transistor may be used as a ____________ and as an _____________

3. Copy and image of a transistor to your document.

4. What are the two types of transistors?  Copy the circuit symbols for the two types of transistors to your document.

Run the simulation here.

1. Put 1 volt for the battery and put the green N-Type Dopant in the left-hand box and the green P-type in the right.  Does the current flow?

2. Make the voltage -1.  What happens to the current?

3. This is an example of how a Diode works in a circuit.  Explain what a diode does in a circuit and find an image of a diode.

4. Answer the following question. The key word is that the transistor is used as an AMPLIFIER:

Put it in the Transistors Folder on SLAMA/Class Folders/Physicsabc

Star Questions:

Do the following in an OpenOffice Document.  You can find OpenOffice in your Applications Folder.

Plasmas

Go to this website about plasmas and answer the questions in a OpenOffice document.

1. What are the states of matter usually found on earth?

2. What is considered the 4th state of matter?

3. list 9 things that are made of plasma (from the poster).

4. What is a plasma?

Magnetic Fields

5. Read the first paragraph here to find out what causes Magnetic Fields.  What causes magnetic fields?

6. Read this to find out about the Right Hand Clasp rule.  Draw a wire carrying a current and draw its magnetic field obeying the right hand rule.

7. Run this simulation.  Click the Electromagnet tab to see how a current in a coil creates a magnetic field.  If you wrap your fingers around the coil in the direction current flows, your thumb points in the direction of the magnetic field.  Draw a coil and the field.

Save the document with your name in the title and the word “plasma” and put it in the Plasma folder in SLAMA/Class Folders/Physicsabc/

1. Write everything I write on your questions.

2. Make a comic:

Title Square: Waves and Circuits

Square 2: v = fλ, what do the variables mean?

Square 3: Ohm’s Law, the equation and what the variables mean.

Square 4: Where does visible light fall in the electromagnetic spectrum?

Square 5: Refraction, what is it?

Square 6 : The Doppler Effect, what changes when you hear the doppler effect?

1. Go over problems 1-17 on the practice test.  Write notes on the test.

2. Create a comic of at least five questions that you had trouble on.

Don’t copy the entire question and answer, just make a square about the physics concept you need to remember.  F=ma, Force Equals Mass times Acceleration and an image illustrating it is fine.

Here are the released test questions.  You can use command-shift-4 to copy images.

Circuit diagram notes

Parallel resistors:

1. Use the Circuit Construction Kit. Make a circuit with two resistors in parallel, a voltmeter, and a non-contact ammeter like the following:

Draw the circuit in your notes using the circuit symbols and find the resistance of the two resistors using Ohm’s Law and the current and voltage reading on the meters.   Then use the parallel resistor equation to find the equivalent resistance.  Click “Show Values” to see the values of the resistors and battery.  You should get the same answer using both methods.

2. Put the voltmeter leads across one of the resistors and use V / R for that resistor to find the current, I, through that part of the circuit.  How does this value compare to the ammeter value for the current thought the circuit?  How much current is probably going through the other resistor?  Draw a the circuit and explain your results.

3. Control-click on the resistor you are measuring and change the resistance either up or down.  With low resistance, what happens to the current through that resistor?  With high resistance what happens to the current?

4. Calculate the current through the resistor in #3 using Ohm’s law.  Calculate the current through the other resistor.  What is the total current through both resistors?   How does this compare to the current through the circuit?

5. Answer this question:  When the current reaches parallel resistors, it ____________ into two paths.  More  current will go through the path of _________ resistance.  Less ________ will go through the path with more resistance.

1. Use the Circuit Construction Kit to create a circuit with a battery, a resistor, a voltmeter, and a non-contact ammeter like the following:

Draw the circuit and measure the voltage across the battery and the current through the circuit, and use Ohm’s Law to find the resistance of the resistor.

2. Add another resistor in series with the first like the following:

Draw the circuit and find the resistance of two resistors in series by measuring the voltage and amperage in the circuit and using Ohm’s law.

3. Add another resistor and find the resistance of all three resistors in series.

4. Write down how the resistance changes when you add resistors in series.

5. Make a circuit with three resistors in it like the following:

Click the show values button to see the resistances of the resistors.  Control click on each resistor and make one resistor 2 Ohms, another 3 Ohms, and another 5 Ohms.  What do you think these three resistors will add up to be?  Measure the voltage across the battery and the current through the circuit.  Use your measurements to calculate the resistance of all three resistors.  What do you get?

Voltage across resistors in series:

1. Measure the voltage across each resistor.  Do the voltages add up to be the voltage of the battery?  Draw this in your notes along with your results.

2. Using the voltage across each resistor, find the current through each resistor with I = V/R.  What is the current through each resistor?  Does this match the current through the whole circuit (using the ammeter)?  Draw this in your notes along with your results.

V = IR is ohm’s law.  V stands for voltage [volt], I stands for current [amp], and R stands for resistance [ohm].  Knowing two of these, you can always find the third.

Examples:

A circuit has a current of 2 amp and a resistance of 5 Ω.  What is the voltage of the power source?

A circuit has a 9 v battery and when you measure the current in the circuit, it’s 3 amps.  What is the resistance of the circuit?

A circuit powered by a 12 v battery has a resistance of 4 ohms.  What is the current through the circuit?

Problems. Write the question in your notes (you may summarize it)and then solve the problem.  No credit will be given for just solving the problem.

1. How much current is in a circuit that includes a 9-volt battery and a bulb with a resistance of 3 ohms?

2. How much current is in a circuit that includes a 9-volt battery and a bulb with a resistance of 12 Ω?

3. A circuit contains a 1.5 volt battery and a bulb with a resistance of 3 ohms. Calculate the current.

4. A circuit contains two 1.5 volt batteries and a bulb with a resistance of 3 Ω. Calculate the current.

5. What is the voltage of a circuit with 15 amps of current and toaster with 8 ohms of resistance?

6. A light bulb has a resistance of 4 ohms and a current of 2 amps. What is the voltage across the bulb?

7. How much voltage would be necessary to generate 10 amps of current in a circuit that has 5 ohms of resistance?

8. How many ohms of resistance must be present in a circuit that has 120 volts and a current of 10 A?

9. An alarm clock draws 0.5 A of current when connected to a 120 volt circuit. Calculate its resistance.

10. A portable CD player uses two 1.5 V batteries in series. If the current in the CD player is 2 A, what is its resistance?

11. You have a large flash light that takes 4 D-cell batteries.If the current in the flashlight is 2 amps, what is the resistance of the light bulb? (Hint: A D-cell battery has 1.5 volts.)

Page 20

Today you will study voltage in a parallel circuit.  A parallel circuit is one where the electrical current splits and has two paths it can go through.

Use this simulation

1. Create a circuit with one battery and one light like the one below and draw the circuit in your notes:

Measure the voltage across the battery and the voltage across the light.  Write down these voltages on the drawing.

2. Create a parallel circuit like the one below and draw it in your notes:

Measure the voltage across the battery and across each light?  Label the voltage readings on your drawing of the circuit.  How does the voltage across each light compare with #1?

3. Add another light in parallel and measure the voltage across each light.

How do the readings compare to #2 and #1?  Do you see a pattern?  Write down what you observe.

4. Compare these results with yesterday’s experiment.  Complete this sentence:  Voltages in a series circuit_______________________ and voltages in a parallel circuit __________________________________.

Amperage

Now create a circuit with an ammeter in it like the following:

An ammeter measures the flow of electrons through a wire.  It’s called “current.”  The current in a wire is like the current in a stream.  It is a measure of how much is flowing through the stream or how much is flowing through the wire.

1. Measure how much current is flowing through the circuit with one lamp in it?

2. Measure how much current flows through a circuit with two lamps in series?

3. Measure how much current flows through a circuit with two lamps in parallel.

4. What kind of circuit allows more current to flow, series or parallel?