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Physics project
 

Physics project

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    Physics project Physics project Presentation Transcript

    • PHYSICS PROJECT BY JAYASHREE VENKATESH
    • How does it works ???      TOUCH SCREEN GLOBAL POSITIONING SYSTEM ( GPS ) MICROWAVE BICYCLE AIR PUMP SPEAKER SYSTEM
    • HOW DOES THE TOUCHSCREEN WORKS ?
    • INTRODUCTION A touch screen is computer display screen that is sensitive to human touch.  The display screen has a sensitive glass overlay placed on it and we could give the desired input by touching it.  A touch screen kit includes a touch screen panel, a controller and a software driver.  Internal touch screen kits are available but require professional installation because the must be installed inside the monitors. 
    • MODEL OF TOUCHSCREEN
    • WORKING OF TOUCHSCREEN Main components are :Touch sensor Controller Driver
    • A touch screen sensor is a clear glass panel with a touch responsive surface.  The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. 
    • The controller is a small PC card that connects between the touch sensor and the PC.  The controller determines what type of interface/connection you will need on the PC. 
    • The driver is a software that allows the touch screen and computer to work together.  Most touch screen drivers today are a mouseemulation type driver. 
    • DIAGRAM SHOWING HOW IT WORKS
    • TYPES OF TOUCH SCREEN TECHNOLOGIES Resistive Touch Screen  Capacitive Touch Screen  Surface Acoustic Wave touchscreen  Infrared Touch Screen 
    • Applications Public Information Displays::: Tourism displays, Trade show display Customer Self-Services::: Stores, Restaurants, ATMs, Airline ticket terminals and Transportation hubs. More uses... Digital jukeboxes, Computerized gaming, Student Registration systems, Multimedia software , Scientific applications etc
    • Pros  Direct pointing to the objects.  Fast  Finger or pen is usable (No cable required)  No keyboard necessary  Suited to: novices, application for information retrieval etc. & Cons Low precision by using finger User has to sit or stand closer to the screen The screen may be covered more by using hand No direct activation to the selected function
    • GLOBAL POSITIONING SYSTEM (GPS)
    • Review of GPS concept
    • Theory of Positioning  Trilateration  Measuring distance  Accuracy of time and location of satellites
    • Trilateration  A method for determining the intersections of three sphere surfaces given the centers and radii of the three spheres. Trilateration Triangulation
    • Simplifying the problem Let’s assume several factors for easy understanding.  GPS Satellites are on the ground (3D  2D)  We know the exact location of satellites  We can calculate the distance from each of the satellites
    • Start with first satellite Your location is somewhere on the circumference of the circle.
    • Second satellite gives two points
    • Real trilateration in 3D space
    • Real trilateration in 3D space
    • Measuring the Distance
    • Speed Equation  GPS receiver uses speed equation to calculate the distance to satellites.
    • GPS satellites use radio signal  Instead of throwing balls, the GPS satellites send radio wave and GPS receivers catch them.  Radio wave fly at the same speed of light. (about 300,000 km/s)
    • Signal from GPS satellites Each satellites continuously transmits messages including :  the time the message was transmitted  precise  rough orbital information (location of itself, ephemeris) orbits of all GPS satellites (the almanac)
    • How a Microwave Oven Works?
    • What are Microwaves?  Microwaves are a form of electromagnetic energy, like light waves or radio waves  Microwaves are used extensively in communications  such as to relay long-distance telephone signals, television programs and computer information across the earth or to a satellite in space.  Good for transmitting information because it can penetrate haze, light rain and snow, clouds, and smoke.  Also used in radars and in detecting speeding cars.  Microwave has become most familiar as the energy source for cooking food.
    • How the Oven Works ? Electricity from the wall outlet travels through the power cord and enters the microwave oven through a series of fuse and safety protection circuits.  These circuits include various fuses and thermal protectors that are designed to deactivate the oven in the event of an electrical short or if an overheating condition occurs.  When the oven door is closed, an electrical path is also established through a series of safety interlock switches. 
    • • Sensing that all systems are set to go, the signal activates triac, producing a voltage path to the high-voltage transformer. • The high-voltage transformer along with a special diode and capacitor arrangement increases the typical household voltage from ~115 volts to ~3000 volts
    • •The magnetron converts the high voltage in to the microwave frequency for cooking •The microwave energy is transmitted into a waveguide •The waveguide feeds the energy to the stirrer blade and into the cooking area •When the door is opened, or the timer reaches zero, the microwave energy stops.
    • MICROWAVE OVEN
    • Electrons from a hot filament would travel radially to the outside ring if it were not for the magnetic field. The magnetic force deflects them as shown and they tend to sweep around the circle. In doing so, they “pump” the natural frequency of the cavities. The currents around the resonant cavities cause them to radiate electromagnetic energy at that resonant frequency.
    • How Foods Get Cooked The microwaves that penetrate the food have an electric field that oscillates 2.45 billion times a second, a frequency that is well absorbed by polar liquid molecules such as water, sugars, fats and other food molecules.  Water interacts with the microwave:    flipping its orientation back and forth very rapidly bumping into one another and producing heat, cooking the food. Glass, paper, ceramic, or plastic containers are used in microwave cooking because the microwaves pass through them  Metal reflects microwaves   Unsafe to have metal pans/aluminum foil in oven, may damage oven
    • HOW DOES THE BIKE AIR PUMP WORKS ???
    • What does a Pump Do? • A pump moves a fluid – A fluid is either a gas (like air or steam) or a liquid (water, oil, coolant, etc.)
    • How does a Bike Pump Work? A piston-cylinder compresses the air and drives it down into the tire  To insure that the fluid does not come back out of the tire, there is a one way valve that stops the fluid from returning into the cylinder
    • HOW DO THE SPEAKERS WORK ???
    • Speakers  Speakers vibrate and push on the air pushing out creates compression  pulling back creates rarefaction  Speaker must execute complex motion according to desired waveform.  Speaker is driven via “solenoid” idea:     electrical signal (AC) is sent into coil that surrounds a permanent magnet attached to speaker cone depending on direction of current, the induced magnetic field either lines up with magnet or is opposite. results in pushing or pulling (attracting/repelling) magnet in coil, and thus pushing/pulling on center of cone.
    • I NSI DE THE SPEAKER 1. 2. 3. Cone Electromagnet ( coil ) Permanent magnet
    • Speaker Geometry
    • PUSH ME, PULL ME When the center of the speaker cone is kicked, the whole cone can’t respond instantaneously the fastest any mechanical signal can travel through a material is at the speed of sound in the material The whole cone must move into place well before the wave period is complete otherwise, different parts of the cone might be moving in while others are moving out (thus canceling the sound) if we require the signal to travel from the center to the edge of the cone in 1/N of a wave cycle (N is some large-ish number): available time is t = 1/Nf = /Ncair ripple in cone travels ccone t, so radius of cone must be < ccone/Ncair basic point is that speaker size is related to wavelength of sound low frequency speakers are big, high frequency are small.
    • Thank you……..