DM1605 Mani

Electronics

The electrical force or ‘pressure’ that causes current to flow in a circuit

What is voltage?

Volts (V)

What are the units for voltage?

The movement of electrical charge, the flow of electrons through the electronic circuit

What is current?

From positive to negative voltages

Which way does current flow?

Amperes (Amps, A)

What are the units for current?

Causes an opposition to the flow of current in a circuit

What is resistance?

Controls the amount of voltage and current in a circuit

What does resistance control?

Ohms (Ω)

What are the units for resistance?

Ohm’s Law

What describes the relationship between current, voltage and resistance?

V=IxR

What is the equation for Ohm’s law

V is the voltage between two points ( measured in Volts)

In Ohm’s Law, what does the V stand for?

I is the current flowing along a path between those two points (measured in amperes)

In Ohm’s Law, what does the I stand for?

R is the resistance of that path (measured in Ohms)

In Ohm’s Law, what does the R stand for?

Volts=Amps x Ohms

What two units do you multiply to find volts

The sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node

What is Kirchoff’s first law?

Where a current must take a single path, going through one component and then the other in a series

What is a series circuit?

A circuit in which the current splits and takes two parallel paths at the same time

What is a parallel circuit?

Draw out a parallel and series circuit

Joules (J)

What is the unit for energy?

Voltage

What is potential difference?

Volts, V

or

Energy per charge, joules per coulomb, J C^-1

What the unit for voltage?

amps, A

or

charge per second, coulombs per second, C s^−1

What is the unit for current?

watts, W

or

energy per second, joules per second, J s^−1

What is the unit for power?

Power=voltage x current

What is the equation for power?

Ohms (Ω)

What is the unit for resistance?

Resistance= voltage/ current

What is the equation for resistance?

A device designed specifically to have a constant resistance

What is a resistor?

They store electrical energy and can be used like a temporary battery

maintain power supply while batteries are being charged

What are capacitors?

They conducts current in one direction and are used to convert AC power to DC power in a diode bridge

What are diodes?

A semiconductor device used to amplify or switch electrical signals and power

low operating voltages

typically found embedded in integrated circuits

What is a transistor?

A circuit in which all or some of the circuit elements are electrically interconnected so that they are considered to be indivisible

They are carriers that are soldered onto a pcb

What’s an integrated circuit

3 x 10^8m/s

What is the value of speed of light?

2\.45 x 10^9 Hz

What is the value of microwave frequency?

1\.6 x 10^-19C

What is the value of a charge on an electron?

m

length

What is the unit symbol and quantity of the meter?

kg

mass

What is the unit symbol and quantity of the kilogram?

s

time

What is the unit symbol and quantity of the second?

A

electric current

What is the unit symbol and quantity of the ampere?

K

temperature

What is the unit symbol and quantity of the Kelvin?

cd

luminous intensity

What is the unit symbol and quantity of the candela?

mol

amount of substance

What is the unit symbol and quantity of the mole?

k

10^3

What is the symbol and factor of Kilo?

M

10^6

What is the symbol and factor of mega?

G

10^9

What is the symbol and factor of giga?

T

10^12

What is the symbol and factor of tera?

P

10^15

What is the symbol and factor of peta?

m

10^-3

What is the symbol and factor of milli?

µ

10^-6

What is the symbol and factor of micro?

n

10^-9

What is the symbol and factor of nano?

p

10^-12

What is the symbol and factor of pico?

f

10^-15

What is the symbol and factor of femto?

A dense, central nucleus surrounded by a cloud of negatively charged electrons

What is an atom?

A mix of positively charged protons and electrically neutral neutrons

Except for a hydrogen atom which only has one proton

What does the nucleus contain?

positive

What charge does a proton have?

Negative

What charge does an electron have?

Neutral

What charge does a neutral have?

Coulombs

C

What is electric charge measured in?

A fixed voltage that can be used to power an electronic device or an electrical system

What is a dc voltage source?

Batteries (chemical)

Generators (Electromechanical)

Power supplies (rectification from ac sources)

What are the three dc voltage sources?

Negative to positive

What direction do electrons flow in current?

The rate of charge transport

What does current describe

I=Q / T

What is the calculation for current?

Coulombs

C

What is the unit for charge?

Materials that allow a large number of free electrons to flow with very little voltage applied

What is a conductor?

copper

gold

aluminium

Examples of a conductor?

Materials that have very few free or no electrons and therefore does not allow current flow

What is an insulator?

Plastics

Wood

Rubber

Examples of insulators?

A specific group of elements that exhibit characteristics between those of insulators and those of conductors

What are semi-conductors?

Silicon

Sulfur

Examples of semiconductors?

A longer wire has a higher resistance

In resistance, what is length, l?

A thicker wire has a lower resistance

In resistance, what is cross-sectional, A?

A value that quantifies how strong a material opposes the flow of electrons, the higher the resistivity, the higher the resistance

In resistance, what is resistivity, p?

R= pl/A

What is the resistance of a prism?

A higher temp causes the ions in the metal to vibrate more making it harder for electrons to move through the metal

How does temperature effect resistance?

A measure of how well a material conducts electricity

What is conductance?

G=1/R

What is the equation of conductance?

G,

measured in siemens, (S)

What is the unit of resistance?

Carbon film

Metal film

Metal-oxide film

Thin/thick film

Wire wound

Name the 5 types of resistors?

A potentiometer

What is another word for a variable resistors?

\-The resistance between the wiper arm and either terminal can be from 0 0hms up to the full resistance value

\-The sum of the two resistances between the wiper arm and each outside terminal is equal to the full rated resistance of the potentiometer

How does a potentiometer work?

Rac= Rab + Rbc

Full rated resistance of a potentiometer equation?

A two terminal electrical component

Stores energy in the form of electrostatic charge

What is a capacitor?

C=Q/V

\
C=capacitance

Q=Charge

V=Voltage

What is the equation of capacitance?

Farad (F)

What is the unit of capacitance?

It charges up

electrons are pushed onto one plate and repelled from the other

when fully charged the capacitor stores charge Q

What happens when a dc voltage is applied to a capacitor?

The capacitor discharges

What happens to the capacitor when voltage is removed and the charge flows back around the circuit?

Two conductive plates separated by a dielectric (insulator)

What does a common capacitor consist of?

What is the equation of capacitance?

\-Ceramic

\-Electrolyric

What are the two types of capacitors?

A passive electrical component that stores energy in the form of a magnetic field

It consists of a wire loop or coil

What is an inductor?

Henry (H)

What is the unit of inductance?

An inductor

coil

ferromagnetic core to improve magnetic field strength

act like a permanent bar magnet with north and south poles

an example of an electro-magnet

What is a Solenoid?

What is the inductance of a solenoid?

Used to change the voltage to a higher or lower without changing the power

What is a transformer?

To increase the voltage

From power stations to grid

What are step up transformers for?

To decrease the voltage

From grid to residential area

What are step down transformers for?

AC voltage

converted into magnetic flux in primary coil

Magnetic flux is converted into current again in secondary coil

Do Transformers work with DC or AC voltage?

Transformer equations?

Magnetization and demagnetization of core (usually iron) will not be perfect. This is known as Hysteresis and some portion electrical energy will be consumed

What is hysteresis loss in a transformer?

Due to Stray fluxes link with the mechanical structure and winding conductors, an e.m.f will be induced which is not useful and hence considered as loss.

What is Eddy current loss in transformer?