Midterm proposal (working with electrons) Kewei Xu

Midterm project proposal

1. Project Title: Light Tunnel

Image result for light tunnel

Just like the picture below shows, my project is similar to a Light tunnel. When an object passes through the tunnel, the light will turn on following the path of object.

2. Project Statement of Purpose

In our daily life, electromagnetism is widely used everywhere. Generating electricity, motor, communication, wireless and so many other aspects are using the knowledge of electromagnetism. Thanks to Faraday, Maxwell and other scientists, we found this amazing relationship between electrons and magnetism. In this project, I tend to utilize this relationship and make some interations between them. This project incorperate the knowledge of generating electricity from changing magnetic field with some art elements, which I believe is the essential idea of IMA and this course.


There are several materials I need for this project.
1. Coils with enough turns
2. Magnets (as strong as possible)
3. Low Power LED light (Lower the power it needs the better)

According to Faraday’s law of electromagnetic induction, any changing magnetic field will induce some electric voltage difference in a close loop. From the equations shown below, the magnitude of the induced voltage is directly propotional to number of turns of the coils and how fast the magentic field changes. This is also related to the materials I required.Theoretically, I will use one coil, which performs as a battery, and one LED combination to be one unit of my project. By introducing a changing of magnetic field around the coil, which is done by passing a magnet through the hole of the coil, there will be induced voltage across two terminals of the coil. Therefore, the LED can be turned on. If one single unit of my project is working, I will connect several of them cascadely and create a “light tunnel”. Whenever a object (which is a magnet) passes through the tunnel, the LED will follow the path of the object turn on/off.

The purpose of this project is to use some scientific knowledge we learnt in class, recreate and test that theory in cooperating with some art elements. Hopefully everything will goes well as I implement everything physically.

I finished a small experiment on Tuesday which works out well using the coil we had in class and a 2V LED. Yeah!




Kinematic Sculpture (Working with electrons) Kewei Xu

Kinematic Sculpture —— Building a magnetic pendulum

The idea of my kinematic sculpture is coming from a pendulum. In a no-friction world, a pendulum will keep moving forever in a constant frequency. Due to this characteristic, the pendulum is widely used in time recording in ancient time (figure 1,2 &3). In my kinematic sculpture, I tended to use one magnet as the pendulum and hung it over in the air. I put another moveable magnet right under the hanging magnet without touching it.

Image result for clock pendulum

Figure 1 Clock pendulum 1Image result for clock pendulum

Figure 2 Clock pendulum 2

Image result for clock pendulum

Figure 3 Clock pendulum 3

My intuition is to give the pendulum an initial force, which makes the pendulum start to swing. At the time it swings close to the underlying magnet, due to the counterforce or attracting force, the underlying magnet will have some movements. And I cautiously set the distance between two magnets, which will enable the force to be not too small, but also ensure they will get contect physically. The following video is recorded in 2 minutes duration, but I only uploaded the first 40 seconds to see the actual result.

The original setting was hanging the string on a metal stick instead of hands in the video, but I made this change in order to have a little control over the whole device. As we can see, when the pendulum passes by the free magnet, the free magnet is moving randomly.

My interpretation of kenematic sculpture is something that doesn’t require the outside forces, or just need some nature outside forces such as wind. Another point I want to illustrate in my kinematic sculpture is that the movement can be completely random or following some patterns. Since many objects follow no law of movement in our world, for example the movement of the electrons. This random is a way of beauty and many artists actually use this unpredictable movement to create many amazing works. On the contrary, some other objects follow some laws, just like the pendulum. This represents how we human interperate the world. We always try to analyze the world and try to find some inside connections, and it works very well in many science problems. This movement can still be a way that we could produce kinematic sculpture.

Lab 5 Ampere Law & Electromagnets (working with electrons) Kewei

Lab 5 Ampere Law & Electromagnets


In this lab, we were going to use the simulation tool, which is a website www.falstad.com, to simulate some circuits and then try to build it with the same component.

Experiment 1Simulation of a charging capacitor

In experiment 1, the RC circuit is built. By switching on the switch at t=0 time, the capacitor starts to charge up. We could see the exponential curve of the voltage across the capacitor and it stablize around 10V, which is as same to the voltage supply. Also, we also observe the exponential decrease of current in this case.

Figure 1 simulation of RC circuit


Experiment 2Measuring a charging capacitor

To charge the 4.7mF capacitor (we use 220 ohm resistor), theoretically TAO would be TAO=RC=220*4.7m=1.034s. To be fully charged, we need 5 TAO, which will be 5*1.034s = 5.17s. In the following record, the scaler is 1s/block, so it’s 5s in total. Theory matches with experiment! yeah!!!!!

Figure 2 Charging the capacitor in real life

Experiment 3Adding loops

Figure 3 simulation of RL circuit

In experiment 3, the RL circuit is built. By switching on the switch at t=0 time, the voltage across the inducor starts at a very high place and decay exponentially. Consequentially, the voltage across resistor starts to increases exponentially. This can be explained easily using Lens Law, which says that inductor doesn’t allow the current to increase sharply.

Experiment 6 Make a solenoid

In experiment 6, a simple solenoid is made using wires and a power supply (this was done by Kevin and Shawn). By closing the switch or connecting the circuit, the inductor will become a big magnet and push out the coil. This function makes the device similar to a “gun”.

Figure 4 the solenoid made by Shawn and Kevin


In this lab, we took many inside experiment with the transient circuits, which includes RC circuit, RL circuit and solenoid. We did them both on simulations based on computer software and physical component, which is very helpful for us to get understand of the behavior of transient circuit.

Lab 4 report (Working with electrons) Kewei Xu



This experiment is aimed at how we can measure and analysis circuit element without directly measure the components.


  • Regulated Power Source
  • Voltage Meter
  • Current Meter
  • Wire
  • LED
  • CR2032 Battery
  • 1k ohm resistor
  • 220 ohm resistor


Experiment 1: Calculating resistance of a wire

By connecting the current meter and wire in series with a low voltage power supply, adjust the voltage level until the current in the current meter is 1mA/1A/2A and calculate the resistance of the wire.

Experiment 2: Measuring internal resistance

We use two batteries together with the output of roughly 2.4V. Use the wire to connect the ends of an LED to the ends of the battery. Pay attention to which prong is positive and which is negative on the LED. With all the readings, we will be able to calculate the internal resistance of the LED.

Experiment 3: Measure power

We use a 1k and 220 ohm resistor and set up a circuit that consumes 1 watt.

Experiment 4: Resistor divider (Run out of time)


Experiment 1:

In this experiment, due to the small resistance of the wire, we could induce 1mA in the circuit steadily.  With 0.11V power supply, the current was 1.16A. With 0.25V power supply, the current was 2.00A.

Experiment 2:

With a red LED, we used two 1.5V batteries which, in total, emit 2.37V as they were not fully charged. The choice of 2 battery was because one battery cannot power up the LED itself. The current reading was 72.5mA.

Experiment 3:

Using a 220 ohm resistor, supplying 14V from the power supply.

Results / Conclusions:

For all the experiement, the schematic is shown in the figure below:

Experiement 1:

By the definition of Ohm’s law, R=V/I, the resistance of the wire can be calculated as 0.1ohm=0.11V/1.16A and 0.125ohm=0.25V/2A.

Experiment 2:

We used two batteries to power a red LED. We noticed that the current started increasing as the resistance started decreasing which shows the relationship between the two values. This indicates that the resistance of the LED will change as the temperature is heating up. The internal resistance of the LED can be calculated as 31.6ohm=2.37V/0.075A when it’s at a steady state.

Experiment 3:

For this experiment, we used 220ohm resistor to produce 1W power. With 14V at  the power supply, the power is at 0.89W=14^2V/220ohm.


These experiments helps us to get familiar with some physical notations such as resistance, power and current. We come to recognize that there are multiple ways to measure some parameters which we can hardly measure directly in our circuit. This would be very useful in the further study of circuit.

Working with electrons: Generating and using electricity (Kewei Xu)

Lab Report


The goal of this lab was to get familiar with instruments and toos to measure and using magnetic field.


There are total four experiments done in the lab.

  1. Using electricity —- get a sense of how much voltage and current is affordable for LED and motor etc.
  2. Making a battery —- using the knowledge for chemistry, building up a battery and do some necessary measurment.
  3. Making a motor —- using the knowledge of electromagnetism to create a motor.
  4. Stepping down and stepping up —- try to step down and step up voltages using transformers.

Data and procedure

  1. In experiment 1, we connected a LED or a motor to a 5V voltage source.
    1. The LED breaks when approximately 8V cross it and 2A current pass through it.
    2. The motor didn’t break in our experiment. We increased the voltage up to about 30V and the current was about 5A, however, the motor still run. But we did see smoke coming out and sparks inside the motor, which indicates that this voltage is no longer its normal operating voltage. Due to limitation of our power supply and the safety concern, we didn’t find the threshold voltage for motor. The video below records the process.
  2. In experiment 2, we successfully create a battery using two oranges. By placing copper and zink strips into the orange and using them as the postive and negative pole of the battery, we were able to detect some voltage across two terminals. The picture below shows how we connected the battery and how we power up a watch.

  3. In experiment 3, we recreated a motor like we did in lab 2. The following video records the setup and the motion.

  4. In experiment 4, we experienced the step down and step up devices using transformer. We successfully created a spark producer after step up devices. The following is the picture for sparking device.


This lab gives us a opportunity to experience how electricity is created and how electricity is used to power up devices. This is truly important for any engineers who wish to work with electrons to understand the inside logic of electricity in order to fully make use of it. By know these knowledge, it’s also helpful for us to avoid any innecessary danger while we are dealling with high voltage devices and using transformers etc.

Research on Kinematic sculptures (working with electrons)

The research on Kinematic sculptures for me is done in a time relevant base. I took a look on what’s the character of kinematic aesthetic representation in ancient time, then I tried to compare them with the comtemperory representation.

Among many kenematic representation, I chose one famous painting from Vincent van Gogh as the sign of Kinematic aesthetic in ancient time.



I chose this picture for one main reason that it shows a very vivid kinematic figure even though it’s actually still. By looking at this picture, one may feel that the clouds, the sky and even the mountain is moving. Actually, this is one main characters for the ancient representation of kinematic figure, which using the static figure to describe the moving object. This is probably due to the technology limitation back then. Compared to the advanced technology and all sorts of energy source, painting may be one of the best ways to accomplish this goal in the ancient time.

For the comtemporary kinematic sculptures, I chose several representatives that I felt really interesting.


“Kinetic sculptures”的图片搜索结果

“Kinetic sculptures”的图片搜索结果

The first one here is done by playing with the shadow and the light source.

The second one is utilizing the power of wind and produce a moving object so that the viewer will observe multiple sides of the sculpture.

The third one is using hundreds of metal. The reflection and the special visual effect of the metal is the main reason why this figure is stunning.

All three kinematic sculptures are very astonishing but all of them are only can be done in the comtemporary society. This also suggests that the technology developement will somehow broaden the way of representation of aesthetic works.

Lab 2 report Kewei (Working with electrons)

Week 2 Lab Report


In this experiment, the objection is to get familiar with the electromagnetism by reproducing the magnetic field and examing the effect of two close magnetic field.


There are total four experiments done in the lab.

  1. Make a instrument that can detect other magnetic fields nearby. This experiment is done by hanging a permanent magnet in the air.
  2. Induce an electrical current through a wire and place it close to the device we did in experiment #1.  In the meantime, measure the current going throught the wire.
  3. Make some change to the experiment #2: instead of using a straight wire, try put the wire into a loop and add more loop to it. Repeat experiment #2 and exam the difference.
  4. Use the knowledge from previous experiments, try build a mechanism that runs like a simple motor.


  1. In experiment 1, we hang one permanent magnet by the string to reduce the fraction. As shown in the video, when we put another permanent magnet close to it, it received some kind of force and start being attracted or rejected to the magnet. It shows that two magnetic field can cause force to each other.IMG_1098
  2. In experiment 2, we connected two 1.5V battery in series and a 1k ohm resistor (in order to protect the battery). The multimeter is also connected into the system to measure the current. The measurement is shown in the picture below and according to my calculation, the number is quite close to my assumption: I = 3V/1kohm = 3mA. The inadequency is may due to the resistance of the wire and the voltage fluctrating of the battery. When we moved the wire near the magnet, we did see some movement of the magnet. This proves that there is indeed some magnetic field produced by the current.

  3. In experiment 3, we added more loops to the wire, and moved towards the magnet again. Comparing to experiment #2, there is more severe reactions from the magnet which means the magnetic field is stronger than before.
  4. In experiment 4, we created one easy motor as shown in the video below. By pushing the coil a little bit, the coil start to spining and won’t stop untill we forced it.IMG_1098


This is a very fun lab since we first examed some very basic principles in the first 3 experiments, such as the interaction between different magnetic fields (experiment #1), current can produce magentic field (experiment #2) and the number of loops will influence the strength of the magnetic field (experiment #3). Finally, we were able to build our motor (experiment #4). After the lab, the basic principles of electromagnetism is more obvious for us and we are ready to use them to produce more advanced devices.

Research in Fengshui (working with electrons)

The geomantic device I choose is the compass shown in the classroom. I choose this devices because I found some more interesting uses of this compass in ancient China.

From learnchinesehistory.com, I learnt that Chinese compass were used as early as the Qin dynasty (221 BCE -207 BCE) or before. Chinese compasses were invented fro more than just helping people find their way when traveling. Compasses were originally developed for aligning buildings with directions (north, south, east or west), and as a tool used in fortune telling.

In ancient China, the master of Fengshui usually used the compass to determine whether a new building is at the right place or certain part of the building, for example the door and the bed, is facing the right direction. Because Ancient chinese were superstition at that time and they want to make sure whether their houses are good for their wealth, family and position in the government. The ancient Chinese compass was not first used as the navigation in travelling, but some divination purpose.

This use of compass actually has some sort of scientific reasonning behind. Normally, the compass will point to the south at any location of the house due to geomagnetism. The master of Fengshui stated that if the compass was not pointing directly to the south at certain position of the house, that place is not suitable for bed. Although sounds supersitious, the magnetism at that place is actually influenced by some kind of mineral under it or some components in the house. If a person sleeps at that place for a long time, the person might has some disease due to the unstable magnetism according to the modern science. Therefore there’s actually some hidden reasons behind the superspitious action of Fengshui.

Week 1 lab report (Working with electrons)

Make a balloon ec-static experiment


Ec-static is used to be a strange phenomenon for people to explain in the ancient time. Some situations might happen when an object becomes ec-static. In this experiment, I used balloon as my experiment target and tried to make a balloon ec-static, then examed the consequences and finally came to a conclusion which explains the phenomenon.


The experiment material contains several balloons, several papers and small piece of styrofoam. There are several preparations to do before the experiment could start. The papers needed to be cut into small pieces and the balloon needed to be inflated.  After all the preparation is done, the following procedures could be done one after another.


  1. By rubbing the balloon back and forth quickly on one’s hair, skirt, sweater or some other materials that are rough on the surface, and putting the balloon close to the paper squares. One important point is that making sure the balloon doesn’t touch the squares directly. An interesting phenomenon is that the paper squares are sticked to the balloon, which requires outside forces to take them off from the balloon.
  2. Repeating similar procedures on the styrofoam. The similar results happen as the paper squares. The styrofoam are attracted to the balloon.


Everything is made up of atoms and atoms are made up of extraordinarily tiny particles called protons, neutrons and electrons. The protons and neotrons are in the middle of the atom and they form the most weight of an atom. The electrons are much smaller and lighter than protons and neotrons, which zoom around the outside. Atoms are neutral under the consideration that the same number of protons and electrons exist in an atom.

When the rubbing happens, some electrons on the sweater, for example, come off and end up on the balloon. Consequentially, the balloon has more electrons than protons and balloon becomes charged with negative charges. On the other hand, the sweaters, for example, is positively charged now.

When the balloon is brought near a little piece of paper or styrofoam, the negative balloon repels the electrons in the paper so part of the paper near the balloon is positive. Since positive and negative attracte, the paper moves toward the balloon. This explains why the paper squares are attracted to the balloon.

This is a very simple experiment that can be done easily at any places. However, it contains lots of knowledge about atoms and what is inside an atom. We should continue looking deeply into the atoms and hopefully more interesting results come out!

Final Project: Fisher (Fish Feeding Machine) (Posted by Paul and Done by Paul And Michael)

“Nothing is impossible.” This is the one sentence that I’ve learned since I joined IMA family. I still remember clearly what I looked like when I first stepped in to IMA lab, I knew nothing about this class, I knew nothing about programming, I knew nothing about what I like. Now, when staring at IMG_2539the final project that Michael and I did together, I can feel that I have grew up a lot. Let’s begin with the final project.

To begin with, I have to mention the idea for our final project.  The picture on the right is the idea for our project. And comparing to our final project, I can proudly say that we achieved most functions
that we want! We managed to switch on/off the light by temperature sensor. We managed to control the motor in a certain distance. And we managed to control Processing by Auduino (Although we didn’t show this function in the presentation). And I will introduce the all functions that our projects have.

IMG_2540One function is the switch on/off light by temperature sensor. Let’s look at this video first.


This video shows this function. How did we do this? The first problem that we met is equipment problem. Since we want to measure the temperature in water, the temperature sensor that we have in the DFrobot Kit cannot do it. Thanks to Prof. Antonius, he helped us to buy a new waterproof temperature sensor, whose name is DS18S20, and I can give you the links to this equipment.

Temperature sensor:


Plus a terminal:
We use these two things to finish this function. And I feel that it’s necessary to show you guys the code that we are using.
Following is the Arduino code:

#include <OneWire.h>

int DS18S20_Pin = 2; //DS18S20 Signal pin on digital 2

//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 2

void setup(void) {

void loop(void) {
float temperature = getTemp();

delay(100); //just here to slow down the output so it is easier to read println(temperature);

if (temperature > 26) { //Here is the part that we use to control light, the others are basically dealing with data.
digitalWrite(7, HIGH);
}float getTemp() {
//returns the temperature from one DS18S20 in DEG Celsius

byte data[12];
byte addr[8];

if ( !ds.search(addr)) {
//no more sensors on chain, reset search
return -1000;

if ( OneWire::crc8( addr, 7) != addr[7]) {
Serial.println(“CRC is not valid!”);
return -1000;

if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print(“Device is not recognized”);
return -1000;

ds.write(0x44, 1); // start conversion, with parasite power on at the end

byte present = ds.reset();
ds.write(0xBE); // Read Scratchpad

for (int i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();


byte MSB = data[1];
byte LSB = data[0];

float tempRead = ((MSB << 8) | LSB); //using two’s compliment
float TemperatureSum = tempRead / 16;

return TemperatureSum;


And I have to thanks Asfand too. We borrowed the light from him. This lamb is connected to Grove Relay, and it’s can original be controlled by clap on/off. We just reconnect it to our project and use the LED code to make it work.
This function is designed for some special requirement that we need because some specific fishes only can live under specific range of temperature. Therefore, we use this light to heat up the water when it’s too cold.
After the light function, here we come to the feeding function, which should be the main topic in our project (whose name is Fish Feeding machine). Sorry that I mention this much not that useful things.
Firstly, we want to say that we use the step motor that we use in the Lab. The only difference that we have is that use a different code. In the Lab, (I can’t remember clearly which lab it is), we use the sample code called stepper-oneRevolution, in our project, we use stepper-onestepatatime. And we change it a little bit to make it can always rotate 180 degrees at one time, and rotate back after press two times. Since the code for this is together with some others code, I will show them later.
Secondly, we add the inferred receiver to our project to achieve remote control. This is an example from Kit, it’s project 14 I think. We also use it to control the movie play and pause in the processing, and this is the place where I said that we use processing talking to Arduino. The related video is below, and the code for it is following.
Video that control the motor by inferred.
Video that control the processing by Arduino.
Code for Arduino.
#include <IRremote.h>
int RECV_PIN = 5;
int ledPin = 3;
boolean ledState = LOW;
IRrecv irrecv(RECV_PIN);
decode_results results;#include <Stepper.h>

const int stepsPerRevolution = 200; // change this to fit the number of steps per revolution
// for your motor

// change this to the number of steps on your motor
#define STEPS 100

// create an instance of the stepoper class, specifying
// the number of steps of the motor and the pins it’s
// attached to
Stepper stepper(STEPS, 8, 9, 10, 11);

// the previous reading from the analog input
int previous = 0;

void setup() {
pinMode(ledPin, OUTPUT);
int switchPin = 12;
pinMode (switchPin, INPUT);

// set the speed at 60 rpm:
// initialize the serial port:

void loop() {
int switchPin = 12;
pinMode (switchPin, INPUT);
if (irrecv.decode(&results)) {
Serial.println(results.value, HEX);

if (results.value == 0xFD00FF) {
ledState = !ledState;
digitalWrite(ledPin, ledState);

if (digitalRead(switchPin) == HIGH) {
else {

void moveMotor() {
//get how many step we want every time
int val = 100;

int previous = 0;

// move a number of steps equal to the change in the
// sensor reading
stepper.step(-val + previous);

// remember the previous value of the sensor
previous = val;

Code for processing:
import processing.serial.*;
import processing.video.*;
Movie myMovie;
Serial myPort; // Create object from Serial class
int val; // Data received from the serial port
void setup()
size(1000, 1000);
// String COM4 = Serial.list()[2];
myPort = new Serial(this, Serial.list()[2], 9600);
myMovie = new Movie(this, “8.mp4”);
void draw()
image(myMovie, 0, 0, width, height);
while (myPort.available() > 0) {
val = myPort.read();
if (val == 0) {
} else {
void movieEvent(Movie m) {
These are all the function that I have got for our final project. I really hope I can learn more about this course, but unfortunately this semester is over. But this is definitely not the last time I stepped into IMA. I love this class, I love Antonius, I love my partner Michael, I really enjoy every moment that I have spent in IMA, all the faculties give me help without any hesitation, Thanks again!