Switches in Circuits

This is a miniature portable key board that can be plugged in and used for sending text messages to friends on the Xbox 360. It draws power from the xbox controller itself and works through the physics concept of circuits. When a button is pushed down, it completes a circuit that then sends an electrical impulse contiguous to a given letter or number on the pad. Each word on screen is created by a complicated set of circuits within the messenger kit. Furthermore, circuits are altered by the addition of a SHIFT button, which can produce capital letters, and a GREEN and ORANGE button. When these buttons are held down, they are able to change what each letter or number does. For example, by holding down the green button and pressing W, the @ sign will appear. This is because the green button + W is a different circuit for the electrical impulse than the letter W alone.

CFL vs. Incandescent

Did you know that the action of switching out an incandescent light bulb for a CFL (compact fluorescent light bulb) in every US household would be equivalent to removing the emissions of 1,000,000 cars? This is possible because of the more energy-efficient design of the CFL. While incandescent light bulbs rely on tungsten filament that uses more energy to produce heat than light, CFLs work using a different design. CFLs are made up of tubes with electrodes at their ends. The electrodes shoot electrons through the argon and mercury filled tubes. In turn, having recieved energy, the gases strike a phosphor coating inside a tube, which creates a fluorescent light. This virtually takes away the heat factor in using up energy. An incandescent light generally produces 15 lumens per watt, while a CFL produces 45 lumens per watt. That is why, when producing the same level of brightness, a CFL only needs a 1/3 of the amount of energy that the incandescent bulb uses.

Gift Cards

Gift cards, along with many other cards used for purchases and identification (like credit cards and security pass cards) use a magnetic stripe (magstripe) to work. A magstripe is made up of thousands of tiny iron based particles that act like bar magnets. These particles are magnetized to face either the north or south pole in order to store information. When you swipe your card, a magnetic reader finds your information and verifies such things as the card's expiration date and amount.

This is a picture of a speaker that uses a variable resistor in the sound knob to control the volume of the sound it produces. The resistance on the electrons flowing through the speaker changes as the knob is turned. When the knob is turned, a strip of metal or other conducting substance is moved, forcing the electrons to travel a longer path than before. According to the resistance equation, extending the path also increases resistance. When resistance is increased, less electrons reach their destination per second and less sound is produced.

The Physics of an Air Filter

This is a picture of an air filter in my house that is meant to capture harmful materials in the air such as dust, cotton, and pollen. The filter is able to do this through the use of technology that is related to what we are learning in Physics right now. Near the front of the filter is a grill, which is called the "corona discharge" and is meant to ionize particles in the air. This electrical field gives extra electrons to the neutrally charged particles in the air. Because dust and other harmful substances are usually large, they are the ones who gain the negative charge produced by the "corona discharge." Further into the filter there is a metal plate with a strong positive charge, to which the now charged particles in the air are attracted to. With most of the harmful materials gone, clean air can flow from the top.

Torque

In the case of a fire, a firefighter would hook up a hose to the valve of this hybrid fire hydrant. He/She would then turn the red wheel to allow the pressurized water in the hydrant to be pushed through the hose and onto the fire. This task would be very difficult without special tools since the wheel's diameter is very large, it is pulled tightly to prevent pressurized water from bursting out of the valve, and is rusty. To turn the wheel, the firefighter would have to exert a significant torque. If the firefighter could not exert enough torque, he/she could increase the lever arm by attaching a clamp to the wheel with a bar attached. The firefighter could then push on the extended bar to turn the wheel, as the force necessary to exert a specific torque is inversely affected by the length of the lever arm.

Torque

Last Friday, we learned the difference between circular motion and rotational motion. While with circular motion we could calculate centripetal forces, with rotational motion we can use an equation to determine torque, which depends on two factors: Force and Lever Arm Distance (T=F*r). In paddling, the more torque you can produce, the faster the canoe will move. In the picture, the measuring tape goes from the handle of the paddle to the typical place where your bottom hand should be. This is effectively the lever arm distance. Paddling coaches say to hold as low as possible on the paddle because as the lever arm distance increases, so does torque.