Capacitors are geometries that can hold charges.
Use Gauss’ Law symmetries to calculate capacitance.
Series and parallel connections.
Dielectrics increase capacitance.
Properties of Exponential Response
Time constant (τ) Definition
Source Free RC Circuit
v(t) of RC Circuit
Time constant of RC Circuit
Problem
Home work Problem 1
Engineering review on AC circuit steady state analysis. Presentation lecture for energy engineering class.
Course MS in Renewable Energy Engineering, Oregon institute of technology
Capacitors are geometries that can hold charges.
Use Gauss’ Law symmetries to calculate capacitance.
Series and parallel connections.
Dielectrics increase capacitance.
Properties of Exponential Response
Time constant (τ) Definition
Source Free RC Circuit
v(t) of RC Circuit
Time constant of RC Circuit
Problem
Home work Problem 1
Engineering review on AC circuit steady state analysis. Presentation lecture for energy engineering class.
Course MS in Renewable Energy Engineering, Oregon institute of technology
With this mantra success is sure to come your way. At APEX INSTITUTE we strive our best to realize the Alchemist's dream of turning 'base metal' into 'gold'.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
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Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
2. Capacitors
• A capacitor is a device
which is used to store
electrical charge ( a
surprisingly useful thing
to do in circuits!).
• Effectively, any capacitor
consists of a pair of
conducting plates
separated by an insulator.
The insulator is called a
dielectric and is often air,
paper or oil.
3. Illustrating the action of a capacitor
6V
10 000μF
6V, 0.003A
lamp
Set up the circuit.
Connect the flying
lead of the capacitor
to the battery.
Connect it to the
lamp.
What do you observe.
Try putting a 100Ω
resistor in series with
the lamp. What effect
does it have?
4. What is happening
• When the capacitor is
connected to the battery,
a momentary current
flows.
• Electrons gather on the
plate attached to the
negative terminal of the
battery. At the same time
electrons are drawn from
the positive plate of the
capacitor
-------
+++++
5. What is happening
• When the capacitor is
connected to the battery,
a momentary current
flows.
• Electrons gather on the
plate attached to the
negative terminal of the
battery. At the same time
electrons are drawn from
the positive plate of the
capacitor
-------
+++++
6. What is happening
• When the capacitor is
connected to the
lamp, the charge has
the opportunity to
rebalance and a
current flows lighting
the lamp.
• This continues until
the capacitor is
completely
discharged.
-------
+++++
7. While the capacitor is charging
• Although the current
falls as the capacitor
is charging the
current at any instant
in both of the meters
is the same, showing
that the charge stored
on the negative plate
is equal in quantity
with the charge stored
on the positive plate.
-------
+++++
mA
mA
8. When the capacitor is fully charged
• When the capacitor is
fully charged the pd
measured across the
capacitor is equal and
opposite to the p.d.
across the battery, so
there can be no
furthur current flow.
-------
+++++ VV
9. Capacitance
• The measure of the
extent to which a
capacitor can store
charge is called its
capacitance. It is
defined by
V
Q
C =
Notice that in reality the total charge stored by the capacitor is
actually zero because as much positive as negative charge is
stored. When we talk about the charge stored (Q in this formula)
it refers to the excess positive charge on on the positive plate of
the capacitor.
++++++++
--------------
+Q
-Q
C= capacitance (unit farad (F))
Q = the magnitude of the charge
on one plate (unit coulombs (C))
V = the p.d. between the plates
( unit volts (V))
10. The effec of a resistance on the
charging and discharging
• Putting a resistor in
series with the
capacitor increases
the charging time
• and increases the
discharging time
6V
2 200μF
11. 6V
Kirchoff’s second la tells us that the e.mf. Must
equal the sum of the pd’s
Vbattery = V resistor+Vcapacitor
Initially the capacitor is uncharged.
At this time Vcapacitor =0
And
V battery= Vresistor
12. 6V
Kirchoff’s second la tells us that the e.mf. Must
equal the sum of the pd’s
Vbattery = V resistor+Vcapacitor
As the capacitor charges
Vcapacitor rises and so Vresistor falls.
From
R
V
I resistor
=
The current through the resistor (and therefore
the whole circuit) falls
13. Time/s
CurrentA
Small R
Large R
R
V
I resistor
=max
I max
I max
I max
For a large resistor the
maximum current, (which is
the initial current) is lower.
The time taken to charge the
capacitor is correspondingly
larger.
14. Finding the charge stored
+++++++++
---------------
Remember that the charge stored
on each plate is the same. Finding
the stored charge is another way of
saying finding the charge stored on
the positive plate.
Time/s
Current/A
The area under the curve
is the charge stored
mA
Charge stored
(Q = It)
15. Discharging a capacitor
Here the 1 000μF capacitor is
charged from a battery and
discharged through a 100KΩ
resistor.
Try timing the discharge with a
charging potential of 3V, 4.5V
and 6V.
Draw a current against time
graph in each case and
measure the area under the
graph. This area will give you
the charge on the capacitor.
Calculate the capacitance of
the capacitor in each case
using
V
Q
C =
mA
V
16. Discharging with a constant current
If the series resistance is decreased continuously as the
capacitor is discharged it is possible to keep the current
constant while discharging the capacitor. The advantage
of this is that the charge on the capacitor is easier to
calculate.
Time/s
Current/A
Q = I x t
18. Exponential decay
Current
μA
Time s
Whether charging or discharging the
capacitor, the current time graph has
this particular form. It is exponential in
form. (The “mathematical” form of a
curve like this never actually falls to
zero though in practice it does).
19. Exponential decay
CR
t
oeII
−
=
oI
e
I ×=
1
Time s
The equation of the curve can be
shown to be
Note that the only variable on the right is t.
When t=CR
CurrentμA
I
o
e = 2.718 so 1/e = 0.368
Where C is the capacitance of the
capacitor and R is the resistance of the
FIXED series resistor
1−
= eII o
oII 368.0=
So C x R is an important value
and is known as the
time constant
20. Exponential decay
Time s
CurrentμA
Io
oI
e
I ×=
1
I = 0.368Io
0.368Io
(0.368)2
Io
RC 2RC
(0.368)3
Io
3RC
The time it takes the current to fall by a factor of 1/e is a constant.
That time interval is RC the time constant
21. Capacitors in parallel
V
Q
C =
The capacitors are in parallel and
therefore there is the same p.d.
across eachQ1
Q2
Q3
V
C1
C2
C3
from
VCQ 11 = VCQ 22 = VCQ 33 =
VCVCVCQQQ 321321 ++=++
VCCCQQQ )( 321321 ++=++
CVQ =
A single capacitor which stores as
much charge (Q =Q1+Q2+Q3) is
represented by:
So C= C1+C2+C3
It follows that capacitors in parallel have a total capacitance which is equal
to the sum of their individual capacitances.
22. Capacitors in series
1
1
C
Q
V =
2
2
C
Q
V =
3
3
C
Q
V =
V
Q1 Q2 Q3
C1 C2
C3
V1 V2
V3
adding
++=++
321
321
111
CCC
QVVV
++=
321
111
CCC
QV
C
Q
V =
++=
321
1111
CCCC
i.e.
A single capacitor which has the same effect is:
So:
23. Capacitors and resistors compared
capacitors resistors
Series
connection
Parallel
connection
321
1111
CCCC
++= 321 RRRR ++=
321
111
RRR
R ++=321 CCCC ++=
24. Energy and Capacitors
C+++++++
------------
During charging the addition of
electrons to the negative plate
involves work in overcoming
the repulsion of electrons
already there.
In the same way removal of
electrons from the positive plate
involves overcoming the
attractive electrostatic force of
the positive charge on the plate
Work is done in moving
the electrons
25. Energy and Capacitors
QVW δδ =
C
+ + + +
- - - -
Imagine the capacitor is
partially charged so that the
charge on the plates is Q
Q
V
+
-
It then acquires a little more
charge δQ.
This involves the work of
moving charge δQ from
one plate to the other.
If δQ is very small V can be
considered unchanged in
which case
Q+ δQ
Remember that the voltage V is the
work done per unit charge:
Q
W
V =
26. Energy and Capacitors
QVW δδ =
V
Q
C =
Q
C
Q
W δδ =
C
+ + + +
- - - - V
+
-
Q+ δQ
And as
So the total work done in giving the
capacitor full charge from 0 to Qfull
Q
C
QfullQ
δ∑0
We can substitute for V
And in the limit as δQ→0
dQ
C
Q
W
fullQ
∫=
0 C
Q
W
full
2
2
=
27. C
Q
W
full
2
2
=
Writing Q fpr Qfull and making use of Q=VC
C
Q
W
2
2
=
V
Q
Q
W
2
2
=
2
2
1
2
1
CVQVW ==
W =the energy stored by the charged capacitor (J)
Q= the charge on the plates (C)
V= the pd across the plates (V)
C = the capacitance of the capacitor (F)