Rectifiers and battery chargers- part a/ Electronics 4th year

Define cycle

A sequence of events that repeat

Voltage divider rule

Are used to predict voltage across the components in a circuit

What does a typical dc meter measure?

Average

If your scope does not have the the ability to display your peak to peak, rms and peak voltages numerically what do you have to do?

Count the number of divisions and Multiply by the volts / division

f

Frequency

GND

Reference to display 0

Define amplitude

The amount of voltage or current

Define average dc

The mathematical average of all the instantaneous values recorded

T

Time

Oscilloscope current probes are available that convert the current into a representative voltage and display it in an wave form True or false?

True

Insulators have a very high electrical resistance ?

True it takes a lot of energy to free the electrons to start current flow. Useful to when conductors need to be isolated

Nano

10 exp -9

Semi- conductors have how many valence electrons?

4

What is a clamp on meter similar to?

A current transformer

What is a transducer?

A device that converts an input value to a signal that the oscilloscope can interpret

Oscilloscopes

Allows us to observe the timing of several instantaneous voltages

Instantaneous values of an ac source

Any point in time on a sine wave, the voltage or current has an instantaneous value

Examples of trivalent material

Boron Aluminum Indium

At room temperature extrinsic material is a what?

Conducting material, Not an excellent one

Once an intrinsic material has been doped the result is what?

Extrinsic material

What are electrons called that are only loosely bound to the atom?

Free electrons

Define sine wave

Graphically represents how the values of an ac voltage or voltage change over a period of time

In ac powered bench type scopes, the reference is?

Grounded and bonded to the oscilloscope chassis. Either the load or scope must be isolated

Oscilloscope applications include measurements of what?

Harmonics Ground fault test current Instrumentation signals

What is frequency measured in?

Hertz

Double subscription notation

Identifies device and polarity

Doping silicon with pentavalent materials ( Material with 5 valence electrons) makes a what?

N-type semiconductor. = free electron easy too move

What type of ammeter. Requires the wiring of the circuit to be opened up and connected to the meter to measure current?

Series Ammeter

DC couples mode

Shows both ac and DC

What are 4 valence electrons referred to as _________ elements

Tetravalent

Define time base

The time interval in seconds,milliseconds, micro seconds that each horizontal division represents

P-type material, what tendency do the electrons have

They have a tendency to shift into holes closer to the positive terminal - leaving new holes behind

Multimeter

Three meters are combined into a single instrument

Effective voltage formula

Veff=Vmax x .707

How is the oscilloscope display the graph

Voltage over time Vertical- amplitude Horizontal- time

Insulators have how many valence electrons

5-8 they have tightly bound to the atoms

What is Doping

A process where adding impurities Only about 1 atom of impurity is for each 12 000 000 atoms of intrinsic material. Sufficient to reduce the resistance of the material.

Ac-Gnd-Dc switch

Ac couple Dc couple Ground- 0v volt reference

What does the trigger control do?

Causes the display to begin its sweep across the screen

What else is the effective value referred to?

Rms value Root mean square

What is time measured in?

Seconds

To measure with a volt meter what do you do?

Select a wnt- ac or dc -test a known voltage P verify that your voltmeter is working - when measuring dc voltage, observed v correct polarity( red to positive and black to negative )

When a oscilloscope measures voltage where would you connect it?

When polarity is critical the probe is connected connected to the first letter of the subscript and the reference lead to the second letter

Average of an ac waveform is what?

0, take a number of points and add up then divide by the # of points Bc ac sine waves are equal they equal zero

Time formula

1 cycle/frequency

Frequency formula

1 cycle/time

What characteristic that is common to good conductors is that they possess how many valence electrons?

1-3 Few valence electrons results in little energy required to dislodge the electron from the atom.

Giga

10 exp 9

Pico

10 exp-12

Milli

10 exp-3

Micro

10 exp-6

Mega

10 exp6

Kilo

10exp 3

Define Effective or rms value

An effective value of an ac voltage is the heating effect- of the ac voltage across a certain value of resistance Compared to The effect of a dc voltage applied to the same resistance Therefore 120 vac produces the same heating effect of 120 dc

Examples of pentavalent material

Arsenic Phosphorous Antimony

What type of ammeter doesn't require the wiring of the circuit to be opened up and connected to the meter to measure current?

Clamp on

What are two styles of ammeters?

Clamp on Series

Define conductors

Conductors have a very low electrical resistance

Direct current

Current that flows in only one direction

Ac coupled mode

Dc removed

Define covalent bonding

Each atom shares is 4 valence electrons electrons with adjoining atoms Causing the material to act as if each atom had 8

Extrinsic semi conductor is what?

Either a N-type P-type

Generally clamp on meters are very accurate Below 100mA

False because the magnetic field is too small

Hertz formula

Hz=cycles/seconds

Frequency and time are what?

Inversely proportional

Doping silicon with trivalent materials (impurities with 3 valence electrons)

Makes a P-type semiconductor

Define peak value

Maximum value of a sine wave, at positive or negative maximim with respect to zero

N-type

Negatively charged

What type of meter performs a continuity check on a circuit

Ohm meter

You compare the measure resistance in what?

Ohms

If two scope leads each have a reference lead, should both reference leads be connect to the circuit or should one reference lead be isolated from the circuit?

One isolated

What is a tetravalent element?

One that has 4 valence electrons A semiconductor Silicon and germanium

Does a digital ohm meter with a reading OL indicate a short circuit or an open circuit?

Over limit Open circuit

Define alternating current

Periodically reverses direction

P-type material

Positive creates a hole space for an electron to move to

A simple dc generator or electronic rectifier supplies what?

Pulsating dc

What happens when both conductors are clamped on a 2 wire equip

Reading would be zero bc the magnetic fields cancel each other out

What do series ammeters require

Require the wiring to be disconnected and connect the ammeter in series

What value does a typical ac meter measure?

Rms Root mean square Vpeak x .707

What does the volts/division selector switch do?

Set the number of volts per division on the vertical scale of the scope screen

The Electrons in the electron cloud around the nucleus of an atom occupy what?

Shells or energy levels

What is the most common used tetravalent element?

Silicon(Si) Although germanium Ge has also been used

Electronic devices made from semiconductors are known as the what?

Solid state devices?

What largely determines the ability of a material to act as an insulator or conductor?

The number of valence electrons

What does a voltmeter measure?

The potential difference between two points

Connecting your volt meter to a voltage greater than the selected range can cause damage to the meter? True or false

True

The average value of a sine wave taken over one complet cycle is always zero. True or false

True- bc the positive values are equal to the negative values. This is why a meter set to dc will read zero when connected to a pure ac source. The ac meter will measure the rms value

How do you measure with an ohm meter?

Turn power off to circuit - isolate the component to be tested. This may require disconnections of a termination point -touch leads together to verify that the ohm mete is working, should be zero ♎️ -touch and hold the leads to either side of components under test - over limit (OL) reading indicates to low of range or an open circuit -0 ♎️ indicates a short circuit or a resistance below the limits of the meter

What are the electrons called that occupy the valence shell?

Valence electrons

What is the outermost shell referred to?

Valence shell

What does the transducer convert the measured quantity to?

Voltage signal and then displays a graph of this voltage vs time

What two things does an oscilloscope display graph?

Voltage vertical Time horizonal

What are 4 oscilloscope controls?

Volts/division selector switch Time base control switch Ac-find-dc switch Trigger switch

Define peak to peak value

Vpp, is the voltage or current from the positive to the negative peak

Does the trigger control allow the scope to be triggered from various selected sources?

Yes- can be trigger D from various selected sources: -Internally generated signal Derived from an input signal -line voltage -externally applied trigger signal

Frequency symbol

f