Sunday, April 16, 2017

Relativity

Albert Einstein

Albert Einstein was a German physicist. He was born on March 14, 1879 in Wurrtemberg, Germany. After graduating school, he taught at Berlin, Zurich, and Prague. In 1921, he won the Nobel Prize for physics. In 1933, he, moved to America and worked at the Institute for Advanced Science in Princeton. While working in Berlin, Albert Einstein researched and published papers on his theories of relativity.  

 

Theory of Relativity

The theory of relativity involves two theories by Albert Einstein. They are the Theory of Special Relativity and the Theory of General Relativity. While studying these theories, he decided that space and time were not separate. They were one entity, which he called spacetime. 


Special Relativity

Special Relativity deals with rest and motion. It questions whether rest and motion are relative or absolute. It also deals with the structure of spacetime. This theory was based on two postulates:

  1. The laws of physics are invariant in all inertial systems. 

  2. The speed of light in a vacuum is the same for all observers, regardless of the motion of the light source


Based on the first postulate, Einstein concluded that absolute rest or motion don’t exist. He concluded that all objects move relative to each other. Everything in the universe is constantly in motion. An example where this is shown is a truck that is moving at 40 mph. If there are two children on the truck who are throwing a ball at 5 mph, relative to the children, the ball is moving at 5 mph and the children themselves are not moving. However, relative to someone standing on the side of the road, they would argue that the children are moving at 40 mph, the ball is moving at 45 mph, and they are not moving. This is also not true because that person is on Earth which is constantly moving. Therefore, there is no such thing as absolute rest or motion. All objects are in motion or at rest relative to other objects.
Based on the second postulate, Einstein explained concepts like time dilation, length contraction, and time travel.

Time Dilation

The equation for speed is speed=distance/time. Since the speed of light is the same for all observers, that means that if distance increases, time must decrease, and vise versa. For example, if a light is being reflected between two mirrors, the light will be moving at the speed of light. If there are two more mirrors, the same distance apart, the light between them would also be moving at the speed of light. The the second set of mirrors were moving, the light would still be going at the same speed, but it would be travelling a greater distance. For the amount of time to remain the same, time must slow down for the second set of mirrors. This is called time dilation.

first set of mirrors

second set of mirrors


Length Contraction

Using the previous example of the two sets of mirrors, length contraction can be explained. Time does not dilate enough for the second set of mirrors to make them travel at the same speed. Instead length contraction occurs. The length between the two mirrors will contract to make up for the extra distance. Einstein concluded that time dilation and length contraction work together to keep the speed of time the same for the two sets of mirrors. 



Time Travel

Time slows down as objects approach the speed of light. Therefore, time stops for objects travelling at the speed of light and for an object travelling faster than the speed of light, time must go backwards. However this has never happened before because objects travelling that fast would gain mass instead of speed and it would take an infinite amount of energy for this to occur. Therefore, time travel is impossible (for now). 


General Relativity

The Theory of Special Relativity deals with objects travelling at constant speeds. The Theory of General Relativity deals with acceleration in the form of gravity and its relationship to spacetime. Einstein described spacetime as almost like a fabric. The fabric of spacetime warped and curved around objects. An example that illustrates this is a trampoline. If a bowling ball is rolled onto a trampoline, the trampoline fabric will curve around the bowling ball. If more balls are rolled onto the trampoline, they will roll towards the bowling ball in the center. This is how Einstein explained gravitational attraction. He described it as the curvature of spacetime. 



Principle of Equivalence

The Principle of Equivalence was part of the Theory of General Relativity. Einstein observed that the gravitational force experienced on Earth is equivalent to the acceleration force experience in space. It is shown with this equation: inertial mass*acceleration = intensity of gravitational field*gravitational mass. 

Black Holes

General Relativity implies the existence of black holes. Black holes are regions of space where spacetime is completely distorted, due to an object’s gravitational force being so strong, so that nothing, not even light, can escape. Black Holes are probably formed when massive stars collapse on themselves. They grow by absorbing the mass around them. 



Wormholes

A wormhole is a structure that connects two points in spacetime, like a portal. They could connect two places relatively close or billions of light years away. Since it connects two points in spacetime, it could hypothetically connect two points in time. The General Theory of Relativity suggests that these exist, but scientists have never discovered any. 
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Bibliography

Sources

Pictures

https://media.giphy.com/media/qIKChkz9K17a/giphy.gif
https://upload.wikimedia.org/wikipedia/commons/d/d3/Albert_Einstein_Head.jpg
http://i2.cdn.cnn.com/cnnnext/dam/assets/160826012942-black-hole-breakthrough-lee-pkg-00002217-full-169.jpg
http://www.popsci.com/sites/popsci.com/files/styles/large_1x_/public/import/2014/wormhole-1440x900.png?itok=U294e_xh
http://www.speed-light.info/speed_of_light/wormhole2.jpg
http://img1.joyreactor.com/pics/post/auto-albert-einstein-relativity-quote-200759.jpeg
http://s2.quickmeme.com/img/0a/0a9286e1ef9c10f3421e25f4cef61455d0559853f1780f90baaf816a0a4ba13e.jpg
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitsRzR0j8uJ72MJzzPnFAkP1CVTBBCon70nxEXEIyEuaL0azVXapZ7meETq9QOOl1fEtc7T-SU2XrfnOrJ9_pKhHxR56KKycihbZqvRfrwBrjDrQI02uJpDDnQ0m-AHgn4HQwUS552hBM/s1600/running.jpg

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Wednesday, January 25, 2017

My Motor

 

Materials:

  • 24 gage metal wire
  • two nails
  • pice of coat hanger
  • various metal strips
  • lamp wire
  • base board (wood)
  • screws
  • gator clips
  • 6 volt battery
  • electrical tape
  • strap iron
  • vise

Building the Armature

When I built the armature, I used two nails, tape, a pice of coat hanger (for the shaft), and 24 gage metal wire. First, I taped two nails together with the heads on opposite ends. Then, I measured where the middle was, and pierced the tape and put the coat hanger through, leaving 2" sticking out on one side. 
After doing this, it was time to wrap the wire. I started from the middle, wrapped it to one side, went back to the middle, crossed over, and did the same to the other side. I left about 2" of wire left over and sanded off the varnish. 




 Building the Field Magnet

For the field magnet, I used a vise and bent strap iron in two places. I used multiple pieces to make the magnet stronger. I made sure that it was wider that the armature so that it could spin freely without interferences. 


 I used metal wire and wrapped it around the base of the field magnet about 400 times. I left about 5" of wire hanging out. After this, I wrapped it with electrical tape to protect it and I sanded off the varnish at the ends of the wire.

Building the Commutator

To build the commutator, I used electrical tape and aluminum foil. I wrapped the tape around the shaft, about 3/4" from the armature. I kept wrapping the tape until the cylinder it created was about 1/2" in diameter. For the terminals, I used aluminum foil. I cut out two pieces and folded them until they fit around about a quarter of the cylinder. I then taped the terminals running lengthwise on the cylinder with one end of the metal wire under each one. 

Making the Supports

I used different sized pieces of metal strips to make the supports for the shaft, brushes, and field magnet. 
  
Shaft support:
I cut two congruent pieces of metal. I then folded them in half length wise to make it stronger. Then, I left about 1/2 inch left at the bottom and folded it 90º. Then near the top, I drilled a hole in each. I made sure these holes were the same height. These holes would hold the shaft over the field magnet. 
I also drilled holes in the bottom so that I could eventually screw them into the wood. 

Brush support:
For the brush supports, I cut out two equal-sized strips of metal. I then left about 1/2" at the bottom and bent them at about 120º. I drilled a hole into the bottoms so that I could later screw them into the base. 
 

Field Magnet support:
To secure the field magnet to the base, I cut out a large strip of metal. I bent it over the base of the magnet to shape it and make sure it was the right size. Then I drilled holes on each side. I positioned the magnet on the wood and secured it by screwing on the support. 
 

Making the Brushes

To make the brushes, I used copper-strand lamp wire. I cut two pieces that were about 1 1/2" each. I then stripped the wire. Using electrical tape, I taped the brushes to the supports. 

 Assembling the Motor

To assemble the motor, I screwed in the shaft supports on either side of the field magnet. I also put the shaft in their supports and made sure the armature was positioned correctly in the field magnet. I then screwed in the brushes on either side of the commutator and made sure the brushes made contact with the terminals. I also taped one of the wires from the field magnet to one of the brush supports. To make the motor run, I connected one gator clip to the other brush support and the other to the other field magnet wire. 

MY MOTOR WORKING!!!!!😀

Lol, jk the video wouldn't work😁. Here's a link to the video instead: CLICK ON THIS!!!
Isn't it beautiful?





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Electromagnetic Motors

Magnets

A magnet has a north and south pole. Two like poles repel each other and two unlike poles attract each other. A magnet produces a magnetic field. This is the space around a magnet. When another magnet enters the magnetic field of another, it can be attracted or repelled based on the poles. A magnet can be created by wrapping wire around a ferromagnetic material such as iron. Sending an electric current through this will turn the metal into a magnet. This technique is used when making motors. 


What is an Electromagnetic Motor?


An electromagnetic motor is a machine that converts electrical energy into mechanical energy. It can also be called an electric motor. The basis of any electric motor is an electromagnet. An electromagnet is created by wrapping loops of wire around a nail and connecting it to a battery. The nail then becomes a magnet with north and south poles. The nail spins when the poles of the magnet and the nail repel each other.

DC Motor

A DC motor is powered by a direct current. This means that the motor is powered by something like a battery. A DC motor always has an armature, field circuit, and commutator. 

AC Motor

An AC motor is powered by an alternating current. This means the motor is powered by generators, power grids, etc. 

Parts of a Motor

A motor is comprised of many different parts that work together. 

Rotor

The rotor is then moving part of the motor. It turns the shaft which then delivers mechanical power. There are conductors in the rotor to carry currents and interact with the magnetic field. This is sometimes called the armature (DC Motors). 

Stator

The stator is the electromagnetic circuit. This is also called the the field magnet. This magnet interacts with the rotor and the poles repelling each other results in it spinning. 


Commutator

The commutator switches the input. They are in contact with the brushes and are connected to the armature with wire. This keeps the motor spinning. It connects everything electrically and completes the circuit. 

History of Electric Motors

The first electric motors were created by Andrew Gordon who was a Scottish monk. Many other people contributed to this with principles, theories, and ideas. The first DC motor was constructed by William Sturgeon. He was a British scientist. AC motors came later than the DC motors. Walter Baily was the first person to build an AC motor. The first AC motors (without commutators) were created by Galileo Ferraris and Nikola Tesla. 

What are they used for?

Electric motors are used everywhere. They are used in fans, blowers, pumps, watches, and cars. They are found in many other tools and appliances because of their simple yet important function. Many things need a type of force to work, and a motor easily supplies that. 

Bibliography

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