2. basic physics

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Indian Institute of Technology, K

ROBOTIX


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W

BASIC PHYS


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THINGS TO BE COVERED

BASIC ELECTRICITY INTRODUCTION TO CAPACITANCE

WORKING OF A MOTOR

INTRODUCTION TO ALTERNATING CURRENT BASIC DIODES

TRANSFORMERS


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W

BASIC ELECTRI


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BASIC ELECTRICITY

What is electric current? Why do we need it?

Why do we get shocks due to it?

What are circuits? How many types of Electric current are ther


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BASIC ELECTRICITY

What is electric potential? What is Potential Difference?

What is Ohms Law?

What are Kirchoffs Current Laws?


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What is Electric Current?

Flow of charge though a conductor. Calculation:

where Q is the total charge and t is the total time.

Unit of Charge is Coulomb (C) and Electricity is A

1 A = 1 C/ 1 S

(?) Charge of an Electron?


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What is Electric Current?


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Why do we need it?

All of appliances around us are based on it We need it to power lights, fans, TVs, Proje

PCs etc..

All of us know how does it feel when powerout?


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Electric Shocks

An electric shock occurs upon contact of a humanany source of voltage high enough

sufficient current through the skin, muscles or hair. Th

current a human can feel is thought to

1 milliampere (mA). The current may cause tissu

or fibrillation if it is sufficiently high. Death cau

electric shock is referred to as electrocution. Genera

approaching 100 mA are lethal if they pass throug

portions of the body
http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Amperehttp://en.wikipedia.org/wiki/Fibrillationhttp://en.wikipedia.org/wiki/Electrocutionhttp://en.wikipedia.org/wiki/Electrocutionhttp://en.wikipedia.org/wiki/Fibrillationhttp://en.wikipedia.org/wiki/Amperehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Voltage


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Circuits


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Circuits


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Types of Electric Current

Electric Current are of two types:

Direct Current (DC)

Alternating Current (AC)


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Direct Current

Direction and Magnitude do not change w Used in torches, battery operated toys, rem

controls, and ROBOTS!

NOT used in supply lines due to TRANSMISLOSSES.


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Alternating Current

Direction and Magnitude constantly changtime. (Generally sine or cosine wave funct

Used in power lines, home appliances.

Comparatively less power loss during trans Can be stepped up and down.


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Electric Shocks

Generally, we use DC in robots, as most oelectronic components like ICs work on DC

A Voltage Range of 5V - 12V is used gen

robots.

At that range, there are low chances of sh


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Electric Potential

Every job requires some WORK to be done Similarly, the moving of charges in a curren

requires some work to be done.

Work done in bringing a unit positive charginfinity to a point, is called potential of that

The SI unit of Potential is Volts (V), named a

famous scientist Alessandro Volta.


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Electric Potential

Potential is relative. Potential of a point is defined b

considering the potential to be zero at infinity.


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Potential Difference

As the name suggest, the difference in the pbetween two points.

Represented as V [Delta V].

Vbetween two points one and two arV12 = V2 V1

Also, V12 = (-)W12 / Q


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Potential Difference

As water current moves from high to low levto gravity, similarly, Electric Current moves f

High Potential to Low Potential.

Therefore, in the direction of current, there

a decrease of potential across any compon


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OHMs Law


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USES OF OHMs LAW

In robotics, we generally use Ohms law to the current flow in a branch.

Appropriate value of Resistors are used, to

required current.


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RESISTANCE

Resistance is a constant used in Ohms law. It is a property of the material and hence v

across materials.

It also depends on the shape and size of aconductor.


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POTENTIAL DIFFERENCE ACROSS RES

V= I x R

We know that moving in the direction o

current causes potential to decrease.


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POTENTIAL DIFFERENCE ACROSS RES

VAC = -I x R1I x R2


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CONDUCTORS, INSULATORS AND SEMI- COND

CONDUCTORS : Materials through which ccan flow.

INSULATORS : Materials through which cur

flow.

SEMI CONDUCTORS : Materials which of

resistance intermediate between the conduc

insulators. Widely used in Electronics Indust


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SUPER - CONDUCTORS

Materials which provide absolutely no resisthe electric current flowing through it.

Example : Few Ceramics

In Problem solving, unless resistance is not swires and components are assumed to be m

super conducting materials. (R = 0)


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SUPER - CONDUCTORS

Since R=0, across super conductors, therefopotential difference across the wires would

V= 0 x I


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KIRCHOFFs CURRENT LAWS

Kirchoffs rules help us determine the magnand direction of current in different branch

circuit.

There are two Kirchoffs Current laws.

JUNCTION RULE (Kirchoffs Current Law)

LOOP RULE (Kirchoffs Voltage Law)


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JUNCTION RULE (Kirchoffs Curre


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JUNCTION


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SALIENT POINTS JUNCTION R

There is no loss (sink) of current at any junct Current entering a junction = Current leavin

junction.

Also known as KCL.


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LOOP RULE(Kirchoffs Voltage


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KIRCHOFFs RULE - EXAMPLE


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W

CAPACITANC


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CAPACITANCE


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CAPACITANCE


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CAPACITANCE

For our purposes, we use capacitance in reccircuit to normalize the current.

It is used for conversion from Alternating Cu

Direct Current.


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W

MOT


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WORKING OF A MOTOR


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WORKING OF A MOTOR


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ALTERNATING CUR


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Alternating Current

Direction and Magnitude constantly changtime. (Generally sine or cosine wave funct

Used in power lines, home appliances.

Comparatively less power loss during trans

Can be stepped up and down.


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GRAPH OF ALTERNATING CURR


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DIO


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ABOUT DIODES

A diode is a two-terminal electronic compoconducts electric current in only one directio

Thus, the diode can be thought of as an

version of a check valve. This unid

behavior is called rectification, and isconvert alternating current to direct curren

extract modulation from radio signals

receivers.

ABOUT DIODES
http://en.wikipedia.org/wiki/Terminal_(electronics)http://en.wikipedia.org/wiki/Electronic_componenthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Check_valvehttp://en.wikipedia.org/wiki/Rectification_(electricity)http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Rectification_(electricity)http://en.wikipedia.org/wiki/Check_valvehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electronic_componenthttp://en.wikipedia.org/wiki/Terminal_(electronics)


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ABOUT DIODES

COMMON DIODES


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COMMON DIODES

Light-emitting diodes (LEDs)

In a diode formed from a direct band-gap semiconductor, such as ga

carriers that cross the junction emit photons when they recombine wi

carrier on the other side. Depending on the material, wavelengths (or

the infrared to the near ultraviolet may be produced[12]. The forwa

these diodes depends on the wavelength of the emitted photons: 1.2

to red, 2.4 V to violet. The first LEDs were red and yellow, and hig

diodes have been developed over time. All LEDs produce incoh

spectrum light; white LEDs are actually combinations of three LEDs

color, or a blue LED with a yellow scintillator coating. LEDs can also b

efficiency photodiodes in signal applications. An LED may be

photodiode or phototransistor in the same package, to form an opto-
http://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Direct_bandgaphttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Photonshttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Scintillatorhttp://en.wikipedia.org/wiki/Opto-isolatorhttp://en.wikipedia.org/wiki/Opto-isolatorhttp://en.wikipedia.org/wiki/Scintillatorhttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Photonshttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Direct_bandgaphttp://en.wikipedia.org/wiki/Light-emitting_diode


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TRANSFORM

TRANSFORMERS


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TRANSFORMERS

A transformer is a device that transfers electrical en

one circuit to another through inductively coupled co

the transformer's coils. A varying current in the first

or primarywinding creates a varying magnetic flux

transformer's core, and thus a varying magnetic field

the secondarywinding. This varying magnetic field invarying electromotive force (EMF) or "voltage" in the

secondary winding. This effect is called mutual induc

STEPPING UP AND DOWN
http://en.wikipedia.org/wiki/Electrical_energyhttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Mutual_inductionhttp://en.wikipedia.org/wiki/Mutual_inductionhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Electromotive_forcehttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fluxhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Inductive_couplinghttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Electrical_energy


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The conversion Relation :


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2. basic physics

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