2June2014

Reviewing Exam Question on Circuit

To very important point I learned about circuits today that I did not understand before:

1. Replace the Amp meter with a wire. 

2. Replace a volt meter with a hole. 

Finding Reactance and Inductance

28May2014

Active Physics: Electromagnetic Induction

This activity required the analyzation of the magnetic flux/EMF produced when certain frequencies, area, and magnetic field are manipulated. This picture represents no rotational frequency.

Here the frequency changed as the area changes. 

In the purple is the response to a series questions that represent the EMF and magnetic flux changes with changing conditions. Questions (1-13)

Active Physics: Magnetic EMF

Here the red bar above is moving creating a induced EMF. This assignment analyzes the motion of the bar and its effects on the magnetic flux and induced EMF. Question (1-8) address these changed and they are affect by the motion of the bar.

Measuring Inductance

Connecting a solenoid to a function generator in series with a resistor 149 Ohm resistor  we can use a oscilloscope to determine the inductance of the solenoid. We can compare this experiment value with a calculated value  and a value from the detector. 

Find the time interval we experimentally determined the inductance to be 0.0116 h. Doing calculations above we determined the theoretical value to be 0.0078h and with a meter we determined the measured inductance to be 0.00739h. 

19may2014

Magnetic Field Produced in each Coil

In this photo you see the set up we used to determine how the number of coils in a solenoid affect the magnetic field. Determining the magnetic field produced per coil with a constant current we were able to determine the length of the wire.

Here is chart of the number of loops N, current I, and Magnetic field produced B(loop). For every trial we found that the number of (B(loop)/(NI)) is similar for loops greater then 1. 

We used the these values to determine the length of the coils as 0.116m which is very large and can be attributed to in accuracy of the magnetic field sensors. 

Magnetic Field Characteristics

Using a solenoid and a magnet a voltage was produced without a power supply. A relationship was determined between the produced magnetic field from solenoid and displacement of the magnet, number of coils, and velocity.

We found that the magnetic field is proportional to the displacement of the magnet, velocity, and number of coils. 

14May2014

Calculating the Magnetic Field of Earth

The magnetic field of the earth was experimentally determined in the classroom but apply a current to a coils and using the coils magnetic field. B(coil)=ulN/2R=B(earth)tan(theta). For B(coil) was determined Biot-Savart Law and a graph of the B(coil) vs tan(theta) created a slope that represents B(earth). The angle made when the current was applied was used to calculate tan(theta).

This is the  experimental set up. 

Here we can see from a few points that the magnetic field of the earth is 2.83*10^-5 T. 

12May2014

Motor with With Magnets!! 

This magnetic motor was created by attaching a power supply to it then giving it a little push. The rotor in this set up is known as a electromagnet while the magnet attached is a permanent magnet. A voltage of 3V was applied to it any faster cause it to heat up and sin too fast. The we switch the leads and the motor rotated in the opposite direction. 

Making a Simple Electric Motor

To create a electric motor we used a cup, tape, 2 strong magnets, sand paper, and power supply. We got the motor working as you can see in the video to the right we then wanted to see it we could hook up the motor in the previous experiment to get it to work also. We were successful and got both motor to work with one power supply hooked up in parallel. 

Current In wire and Magnitude of the Magnetic Field. 

The current in the is indicated on the white board. We predicted what the magnitude at each number in the picture will be. And tested it with a compass to figure out how much it moves from its original position. 

At point 1 we found that the current in opposite direction cancels out the magnetic field and the magnet in the compass does not move at all. At location 2 when the current goes in the same direction the magnetic field was double and the compass moved double the distance it did at point B. And at point 3 it only moved the same distance it did in B. 

7May2014

Direction Around Magnet

A Magnet was place in the middle of a circle with the N and S poles labeled. The direction that the red arrow was pointing as it was moved around the magnet was labeled. We had the result that the North side of the magnet pointed away from the the north-side and goes all the way around to the South side of the magnet. This indicated that the red end of the compass needle is North and that is why it pointed toward the south. 

Magnetic Field Lines Around a Magnet

We wanted to determine how the magnetic field lines appear so we took a very large magnet with both a North and South Pole at the ends and sprinkled a bunch of Iron fillings on it. We can see that at the poles the magnetic field lines point out and curve around in a circular pattern.

Here is a diagram of what we saw in the previous picture.  

Using this picture we were about to conclude at what location the magnetic field is zero or where it adds. As you can see when the amount of field lines enter a circle and exit in equal quantities the magnetic field is zero. This is similar to what we saw in a electrical field. 

Metal Bar Experiment

Applying a Current of 11.5A to a magnet and placing a metal bar inside the magnet in order to calculate its displace and eventually determining the magnitude of the magnetic field. 

Using the time to took for the metal copper rod to travel distance of the board we were able to calculate the magnetic field to be 2.5*10^-3 Tesla. 

5May2014

One Transistor Amplifier

 This is the circuit diagram for the set up that we used on the breadboard in order to produce a sound that is amplified.  

Here is a close up view of the actual board in this instance it is connected to the oscilloscope. 

This wave formation shows the a saturation of the amplifier with the wave produced from the function generator. 

NEXT:

This is the Circuit diagram used to create a actual sounds when connected to the speaker. Here you can see the resulting circuit board on the right.

Everyone at this point is enjoying the music that resulted from this experiment. And this was a effective method of creating sound.

30April2014

Studying the Oscilloscope

 The plates on a oscilloscope help us direct the electron beam. In this photo we are analyzing the way the length of the plate, and distance between the plates affect the acceleration of the electron flowing through it.  

Oscilloscope Controls

Intensity Control: Brightness

Focus: Focuses the beam

Time/Div: controls how fast the beam moves across the screen per division. 

Measuring The Voltage with a Oscilloscope. 

Here a oscilloscope was used to determine the voltage produced by the battery which was 1.5 V. We learned that with a switch and changing between the ground and DC current we could determine the voltage produced by a battery.  

Measuring Wave Forms

A frequency generator was connected to the channel1 input with a frequency of 96Hz. The period is determined to be t=(6*0.002)=0.012s. Period calculated from the frequency generator t=1/96Hz=0.0104 which is very close to the estimated value of the period from the oscilloscope. 

Switching to the AC/DC button and setting it to the triangle wave produced this pattern.

Here is the result of the upper triangular wave. 

This is the result of the square wave. 

Oscilloscope with DC andAC Power Supply

For this DC power supply it was extremely difficult to determine the amplitude and the frequency. But we  determined the amplitude to be around 30mV. We were not sure how to determine the frequency of this wave because we were not sure how to determine where the wave begins and ends effectively with this method. 

This is a cosine wave that was produced from a AC power supply. The sinusoidal wave made it easier to determine the amplitude, period and frequency.  The Amplitude was determined to be 15V, the period t=(8.5*.002)=0.017s, and the frequency f=1/t=1/0.017= 58.8Hz. 

Liassajous Figures using AC Transformers

We set the function generator to 60Hz connected to channel1 and the AC transformer to the channel2 input. A circle is produced. Lets compare this to half the frequency input. 

We set the function generator to 30Hz connected to channel1 and the AC transformer to the channel2 input. This twisted shaped appear on the screen. This appears to 1/2 of the frequency of the circle above at 60Hz twists the circle to create two circles 

Mystery Box Experiment:

Red/Black and Red/Green and Red/Blue Produced 

Red/Black and Red/Green Produced the same square wave with a A=1.25V and a period for Red/Black t=0.004s, and Red/Green t=0.004s

Black/Yellow and Red/yellow also produced the same wave with a resultant period of 4ms and amplitude .5V. 

 Finally the Black/Green and Black/Blue and Blue/Green also produced a odd wave as summarized in the table below. 

We couldn't conclude what the mystery box is made of but it does have alot of similar wave produced.