This document summarizes information about several physics projects: a touch screen, GPS, microwaves, bike pumps, and speakers. It provides details on how each system works through explanations of components and diagrams. The touch screen section describes the main parts of a touch screen including the sensor, controller and driver. It explains that touching the sensor causes a voltage change that is detected by the controller. GPS is described using the concept of trilateration to determine location from distances to multiple satellites. Microwaves are used to heat food by oscillating water molecules. Bike pumps compress air that is stopped from exiting by a one-way valve. Speakers work by an electromagnet vibrating a cone to create pressure waves in

1. PHYSICS PROJECT
BY
JAYASHREE VENKATESH

2. How does it works ???





TOUCH SCREEN
GLOBAL POSITIONING SYSTEM
( GPS )
MICROWAVE
BICYCLE AIR PUMP
SPEAKER SYSTEM

3. HOW DOES THE
TOUCHSCREEN WORKS
?

4. 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.


5. MODEL OF TOUCHSCREEN

6. WORKING OF TOUCHSCREEN
Main components are :Touch
sensor
Controller
Driver

7. 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.


8. 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.


9. 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.


10. DIAGRAM SHOWING HOW IT WORKS

11. TYPES OF TOUCH SCREEN TECHNOLOGIES
Resistive Touch Screen
 Capacitive Touch Screen
 Surface Acoustic Wave touchscreen
 Infrared Touch Screen


12. 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

13. 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

14. GLOBAL POSITIONING
SYSTEM (GPS)

15. Review of GPS
concept

16. Theory of Positioning
 Trilateration
 Measuring distance
 Accuracy of time and location of
satellites

17. Trilateration
 A method for determining the intersections
of three sphere surfaces given the centers and
radii of the three spheres.
Trilateration
Triangulation

18. 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

19. Start with first satellite
Your location is somewhere on the circumference of the circle.

20. Second satellite gives two points

22. Real trilateration in 3D space

23. Real trilateration in 3D space

24. Measuring the Distance

25. Speed Equation

GPS receiver uses speed equation to calculate the
distance to satellites.

26. 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)

27. 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)

28. How a Microwave Oven
Works?

29. 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.

30. 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.


31. • 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

32. •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.

33. MICROWAVE OVEN

34. 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.

35. 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

36. HOW DOES THE BIKE AIR
PUMP WORKS ???

37. 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.)

38. 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

39. HOW DO THE SPEAKERS
WORK ???

40. 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.

41. I NSI DE THE SPEAKER
1.
2.
3.
Cone
Electromagnet ( coil )
Permanent magnet

42. Speaker Geometry

43. 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.

44. Thank you……..