Energy and Capacitors Remember that the voltage V is the work done per unit charge: Imagine the capacitor is partially charged so that the charge on the.

Slides:



Advertisements
Similar presentations
STRAIGHT LINE GRAPHS y = mx + c.
Advertisements

Ch 29 : Electric Potential and Electric Potential Energy
St Columba’s High School Electricity and Electronics Capacitors.
Unit 2 Day 3: Electric Energy Storage Electric potential energy stored between capacitor plates Work done to add charge to the capacitor plates Energy.
Day 4: Dielectrics & Their Molecular Description Definition of dielectric material Effects of the presence of dielectric material in a capacitor The electric.
Example: a parallel plate capacitor has an area of 10 cm 2 and plate separation 5 mm. 300 V is applied between its plates. If neoprene is inserted between.
Capacitance Chapter 18 – Part II C Two parallel flat plates that store CHARGE is called a capacitor. The plates have dimensions >>d, the plate separation.
17-7 Capacitance A device that stores electric charge Two plates that are separated by an insulator Used in electronic circuits Store charge that can later.
Objectives: 1. Define and calculate the capacitance of a capacitor. 2. Describe the factors affecting the capacitance of the capacitor. 3. Calculate the.
Lecture 8 Friday January 30 Capacitors and Review.
Capacitance Physics Department, New York City College of Technology.
ECE 201 Circuit Theory I1 Capacitance Capacitance occurs whenever electrical conductors are separated by a dielectric, or insulating material. Applying.
Today5/7  Questions?  Circuits and Capacitors  Course Evaluations.
ECE 201 Circuit Theory I1 Natural Response of an RC Circuit.
Qwizdom questions for Jan. 15, One coulomb per volt is a A.joule B.electron-volt C. farad D. watt.
4.4 Fields Capacitance Breithaupt pages 94 to 101 September 28 th, 2010.
 Devices that can store electric charge are called capacitors.  Capacitors consist of 2 conducting plates separated by a small distance containing an.
Book Reference : Pages To understand what a capacitor is 2.To understand their applications 3.To understand how we define capacitance.
Capacitors. A capacitor is a device which is used to store electrical charge ( a surprisingly useful thing to do in circuits!). Effectively, any capacitor.
1 CAPACITORS 2 BASIC CONSTRUCTION INSULATOR CONDUCTOR + - TWO OPPOSITELY CHARGED CONDUCTORS SEPARATED BY AN INSULATOR - WHICH MAY BE AIR The Parallel.
APHY202 9/21/ Capacitance   Ratio of the charge on a conductor to the potential difference between the conductors.   Units of farads (F)
Capacitors Circuit symbol + -. Experiment: To find how the charge on a capacitor varies with potential difference across it. Potential difference across.
Which of these configurations gives V = 0 at all points on the y-axis? 4) all of the above 5) none of the above 10. Equipotential Surfaces III 1) x +2.
Chapter 18.2 Review Capacitance and Potential. 1. A 5 μF capacitor is connected to a 12 volt battery. What is the potential difference across the plates.
AQA Physics Gravitational Fields, Electric Fields and Capacitance Section 6 Capacitors.
Capacitor An element that stores charge when a voltage is applied
Capacitors, Batteries. Capacitors Create a difference in Potential based upon how much charge is stored V = q/C (V) C : Capacitance C = k ε o A /d k :
The two conductors a and b are insulated from each other, forming a capacitor. You increase the charge on a to +2Q and increase the charge on b to –2Q,
Electric field, Electric Potential Difference and Capacitance.
Run the animation for the initial set of values. According the resulting graph and phasor diagram, we would say that the voltage across the capacitor ________.
Define Capacitance and the Farad. G482 Module 2 - Capacitors.
Physics 212 Lecture 8, Slide 1 Physics 212 Lecture 8 Today's Concept: Capacitors How does a capacitor behave in a circuit? More circuit examples.
Do now: NCEA ) Calculate the total capacitance 2) Calculate the total charge stored in the capacitors 3) Calculate the total energy stored in the.
Time constant Is the time it takes for V (or I) to change by 63% of its value If C is large, more charge can be stored, so takes longer to fill/empty.
Power Supply (so big you never notice the level going down) Tap Capacitor V Area represents capacitance, C Volume represents charge, Q Capacitor Model.
Chapter 19 Summary Bare-bones Style i.e. stuff you need down COLD.
The Capacitor A capacitor is an electronic device which can store charge. The symbol for a capacitor is: Capacitance is measured in Farads (F) or, more.
Physics 212 Lecture 8, Slide 1 Physics 212 Lecture 8 Today's Concept: Capacitors Capacitors in a circuits, Dielectrics, Energy in capacitors.
Electrical Energy. Electric Potential Energy Note: Energy is scalar, so keep the sign on the charge +d means movement in the same direction as the E-field.
Consider a charged capacitor whose plates are separated by air (dielectric constant 1.00 ). The capacitor is electrically isolated from its surroundings.
Book Reference : Pages To understand that when a capacitor is charged it stores energy 2.To be able to calculate the amount of energy stored 3.To.
What charge exists on a 30 μF capacitor (fully charged) with a 120 V potential difference between its plates and what is the energy stored? Ans: 3.6.
Capacitance What do you expect to happen when you close the switch? Actually nothing doesn’t happen - as you well know, one wire “becomes positive and.
CAPACITORS. IF A CAPACITORS JOB IS TO STORE ELECTRICAL CHARGE, WHERE WOULD THEY BE USEFUL?
Review Question Describe what happens to the lightbulb after the switch is closed. Assume that the capacitor has large capacitance and is initially uncharged,
Capacitors A capacitor is a device that has the ability “capacity” to store electric charge and energy.
Capacitors. What is a capacitor? Electronic component Two conducting surfaces separated by an insulating material Stores charge Uses –Time delays –Filters.
Capacitors & Exponential Decay. Unit Structure 1.Electric and magnetic fields 2.Capacitors and exponential decay 3.Nuclear physics 4.Medical imaging 5.Modelling.
Example: a parallel plate capacitor has an area of 10 cm2 and plate separation 5 mm. 300 V is applied between its plates. If neoprene is inserted between.
Plan for Today (AP Physics I)
Capacitance Capacitance occurs whenever electrical conductors are separated by a dielectric, or insulating material. Applying a voltage to the conductors.
Revision Tips - Electricity
Capacitors Construction and charging and discharging.
Course work Next week we are doing another PRACTICE course work
ENERGY STORED BY A CAPACITOR
Capacitors, Batteries.
Capacitors.
Lecture 09 - Inductors and Capacitors
Here is the graph of a function
Natural Response of an RC Circuit
Chapter 3 Inductance and Capacitance
Capacitor Question Practice
What charge exists on a 30 μF capacitor (fully charged) with a 120 V potential difference between its plates and what is the energy stored? Ans: 3.6.
Natural Response of an RC Circuit
Capacitance Capacitance occurs whenever electrical conductors are separated by a dielectric, or insulating material. Applying a voltage to the conductors.
IN THE SPOTLIGHT!!!.
Express the Farad in S.I units
Concept 0 - Capacitance C = q V C = capacitance (Farads)
Capacitance Capacitance occurs whenever electrical conductors are separated by a dielectric, or insulating material. Applying a voltage to the conductors.
Lesson Starter 06/03/19.
Presentation transcript:

Energy and Capacitors Remember that the voltage V is the work done per unit charge: Imagine the capacitor is partially charged so that the charge on the plates is Q 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 Q + + + + + V - - - - - C

Energy and Capacitors And as Q+ δQ + + + + + V - - - - - C We can substitute for V C So the total work done in giving the capacitor full charge from 0 to Qfull And in the limit as δQ→0

Writing Q fpr Qfull and making use of Q=VC similarly 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)

Q=VC implies that graphs of Q against V must be straight line graphs Energy Stored Q=VC implies that graphs of Q against V must be straight line graphs The gradient here is C Q W =1/2 QV V

Energy Stored The gradient here is 1/C V W =1/2 QV Q

We know we have The constant current means that we can work out the charge delivered from Q=It = 10 x 10-6 x 20 = 200 x 10-6C Now apply