Electricity

Our latest unit in physics class is Electricity. An electric current is a flow of electric charge. A conductor allows energy to flow easily while an insulator makes energy flow difficult. The current of a circuit is equal to the voltage divided by the resistance. Each energy source, such as a battery, provides voltage. Each resistor provides resistance and lowers the current.

There are three types of circuits. They are series, parallel, and combination (a mixture of the two). In series, resistance lowers current. In parallel, resistance increases current.

These two light bulbs are connected in series. That means that the resistance is higher, because in series, with every new bulb added, the resistance grows higher. Because of this, the current is lower, which is why the bulbs are less bright than the bulb in the previous picture. If one of the bulbs is removed, the circuit would be interrupted and the other bulb would go out, too. The current is the same in both of the bulbs. The voltage would depend on the voltage in each battery. These would be added together and equal the total voltage in the circuit.

These two bulbs are connected in parallel, so with each new bulb added, the resistance is lowered. The current would be higher in this circuit than the previous one because of this. If one bulb was removed, the other bulb would stay lit because the circuit would not be interrupted. If the two bulbs had a different amount of resistance, then the current in the bulbs would be different. The voltage in each light bulb would be different if the resistance in each bulb is different.

This is a complex series. It has two bulbs connected in parallel, which is connected in series to one other bulb. The voltage would be different in the two parallel bulbs if the resistance was different. The two bulbs connected in series would have the same voltage. The current would be the same between those two bulbs as well. The resistance is lowered for each parallel bulb added and it is increased for each series bulb added. The current in this circuit would equal the voltage of each battery added together divided by the equivalent resistance. If the series bulb is removed, the circuit would be interrupted and the other lights would go out. If the bulbs connected in parallel were taken out, the circuit would not go out because the circuit would not be broken.

Zombie Killing in Physics Class

Our latest project in physics class was to build an amusement park attraction. My group created a hall of mirrors based on the ipod game Stupid Zombies. A laser was reflected from different mirrors to hit a zombie on the opposite wall. Our attraction was based on the physics concept of geometric optics and the law of reflection. Ultimately, I had a great time building my Stupid Zombie hall of mirrors.

Stupid Zombies Hall of Mirrors on Prezi

Photo Opp!

Our latest assignment  was to take a photo demonstrating physics concepts for the AAPT Photo Contest. My photo will be entered into the contrived category. I took a picture of my self in a fish tank. The two sides of the tank reflect my image from different angles, which results in the appearance of two virtual images produced. This is because light obeys the law of reflection, which states that the angle of incidence is equal to the angle of reflection. After the light enter the first glass side, it is refracted, and the angle is changed a bit, which results in a slightly differently positioned image on the second side. Flat mirrors produce an image that is upright, the same size, and virtual. The fish tank is a very smooth and produced a specular reflection. A specular reflection is clear and easy to see. The swirls in the picture are from the wall behind the fish tank. I am very proud of my picture in the fact that I was able to produce a picture that reveals several physics concepts.

Electromagnetic Waves

Electromagnetic waves are basically waves of energy caused by a vibration. Based on their wave length and frequency, they are organized on the Electromagnetic spectrum. They usually travel at the speed of light (really really fast).What makes all electromagnetic waves similar is that they can travel through a vacuum, unlike mechanical waves which only travel through mediums.

From: http://www.astrosurf.com/luxorion/Radio/spectrum-radiation.png

The Waves in order of biggest wavelength to smallest.

1. Radio Waves

2. Micro Waves

3. Infared Waves

4. Visible Waves

5. Ultraviolet Rays

6. X-rays

7. Gamma Rays

8. Cosmic Rays

X-Rays

These are very powerful waves that can go through most anything. They are used to see inside people when they have injuries. They are also used at security at airports in order to see into people's bags. Sometimes they are used by astronomers to locate objects not detectable by the human eye. X-Rays can cause cell damage and cancer. This is why radiologists do not stand in the same room when taking an X-Ray of a patient. Lead can deflect this radiation, which is why patients wear lead blankets during X-Rays. Many days of exposure can pose serious risks.

Frequency: (5*10^15)-(1*10^19) Hz

Wavelength:(8*10^-8)-(1*10^-11) m

From: http://www.justcolleges.com/images/bnr_xray-schools.jpg

Infrared Waves

These waves are given off by hot objects, including our own bodies. They are used in television remotes, in heat lamps, and telephones. Night sight goggles or additions to weapons use infared in order to see and criminals can be tracked by looking for infared waves that their body gives off. They also are used in security systems and to track the weather. Infrared waves are used extensively in the military. High settings of infrared directed towards the eyes can harm vision.

Frequency: (8*10^10)-(4*10^14) Hz

Wavelength: (1*10^-3)-(6*10^-6) m

Sources:

http://school.discoveryeducation.com/lessonplans/interact/electromagneticspectrum.html

http://www.darvill.clara.net/emag/index.htm

Using up lots of Energy

Our latest unit is Energy. We have learned how energy is transformed in different processes. We learned how to make energy flow diagrams, identify the system, and calculate work. We also learned how to calculate power, and identifying how the energy is transformed in each problem. We learned how to calculate kinetic energy, potential energy, elastic potential energy, and mechanical energy. For a reflection on this unit, we chose an application and had to explain the system, the energy stored, and the energy transformations. I chose cheerleading basket tosses and used Prezi. In my example, air resistance is negligible.

Energy on Prezi

Photo Credits:

1. www.freewebs.com
2. www.sharonanndance.co.uk
3. www3.wallacestate.edu

Busting Myths and Other Dangerous Activities of Physics

For a creative approach to a lab on forces and Newton's laws, our teacher gave us two myths that are commonly accepted. We were instructed to design an experiment for each myth, trying to disprove it. I worked in a group with Matt, Ford, and Blaine.

Myth One: An object always moves in the direction of the net force exerted on it.

Materials:

1. Baseball

2. Baseball Bat

3. Ford

Procedure:

1. Ford will toss the baseball up in the air.

2. Ford will hit the baseball with the baseball bat.

3. We will observe the baseball until it hits the ground.

Prediction: If it is true that an object always moves in the direction of the net force exerted on it and we observe the tennisball after the bat is no longer applying a force on it, the ball should drop straight to the ground or .

Free Body Diagrams:

1. Baseball bat hitting baseball:

2. After baseball bat has hit baseball, while baseball is still in the air:

Sum of the forces:

1. 

2.

Observations: After the baseball bat was no longer applying a force on the baseball, the baseball did not drop straight to the ground or move backward in the horizontal direction. Despite that the only forces working on it were air resistance and gravity, the ball continued to move forward in a horizontal direction, officially busting this myth.

Myth Two: An object always changes its motion if there is a force exerted on it by other objects. 

Materials:

1. Blaine

2. Ford

Procedure:

1. Ford will run full speed towards Blaine who is stationary.

2. We will observe Ford's movement after Blaine applies a force on him.

Prediction: If it is true that an object always changes its motion if there is a force exerted on it by other objects and we observe Ford's collision with Blaine, then Ford's motion will change after hitting Blaine.

Free Body Diagrams:

1. Ford before colliding with Blaine:

2. Ford when force is applied by Blaine:

Sum of the Forces:

1.

2.

Observations: Ford's motion did not change after his collision with Blaine because the force he applied was greater than the force that Blaine applied on him. This myth is officially busted.

Conclusion:

1. Are there any myths you couldn't disprove? Does this mean these myths are proven?

Though my group was able to disprove both myths, if a myth was not disproved, that does not mean it is proven. The experiment that you picked could have just been one case where it works, while there is another that could disprove it.

2. For each of the myths you "busted", explain why people still believe they are true.

These myths are based off of common sense. For myth number one, this is the case most of the times, however, it is not always true in situations such as projectiles. For myth number two, also seems like common sense, but people forget that if the force applied on the object is too small, it will not affect it.

Video of Experiments: