How We Load Power Supplies. All sources have an EMF. EMF is the open terminal voltage of the battery. All sources have a certain amount of internal resistance.

Slides:

Advertisements

Similar presentations

Current Electricity & Ohm's Law.

Advertisements

Internal Resistance.

Cells have positive and negative electrodes.

Series and Parallel Circuits

Internal Resistance and Resistivity in DC Circuits AP Physics C.

What are we doing today? Internal Resistance Emf Using a graph to find the internal resistance and emf of a potato cell.

Circuits Series and Parallel. Series Circuits Example: A 6.00 Ω resistor and a 3.00 Ω resistor are connected in series with a 12.0 V battery. Determine.

Electricity refers to the presence of electric current in wires, motors, light bulbs, and other devices. Electricity carries power. Power (P)

Kirchhoff part 2. Starter 1.5Ω Learning objectives State Kirchhoff’s second law Apply Kirchhoff’s second law to circuits Solve circuit problems involving.

Electricity. Starter:  What is current?  What is it measured in?  What is it measured by?  Which is the series and parallel circuit? (see board)

Electricity Unit 1 Physics.

Electric Currents Topic 5.2 Electric Circuits. Electromotive Force Defining potential difference Defining potential difference The coulombs entering a.

4.2.3A Ohm’s Law & Circuit Basics Why Make Electrons Flow Anyway?

Current Electricity. Producing Current Current: Flow of charged particles Cell: Source of conversion of chemicals into electric energy. Types of Cells:

Electricity Define Electricity: Electrons: Short Circuit: Current: Battery: Voltage:

Measurement of internal resistance. 1. Connect up circuit shown opposite. 2. Measure the terminal pd (V) with the voltmeter 3. Measure the current drawn.

Unit 7: Electricity and Magnetism

Do Now Describe what you think happens electrically when you dim a light.

Definition of Potential Difference p.d. of 1 Volt when 1 joule of work is required to move 1 coulomb of charge. Example Calculate the work done in moving.

Electrical resistance Resistance measures how difficult it is for current to flow.

19.4 Sources of electromotive force

Potential difference and electromotive force.

(1)A source voltage, that is, an electron pump usually a battery or power supply. [ ENERGY IN] (2) A conductor to carry electrons from and to the voltage.

Short circuiting a battery demo… Dangerous ? High current?

Voltage, V Voltage tells us how hard a positive charge is pushed between two different points. Something, such as a battery, is needed to create a voltage.

Current of Electricity Electric Current Potential Difference Resistance and Resistivity Electromotive Force.

Module 2: Series DC Circuits. RecapRecap Do you still recall these?

Regents Physics Chapters 17/18 Circuits  Series Circuits.

describes the relationship between current, voltage, and resistance greater the voltage across a device with resistance, the greater the current through.

Electromotive Force and Internal Resistance Before we start, the golden rules from GCSE:  The ? through any components connected in series is the same.

Unfortunate book names:. A circuit must contain a source of potential difference, and a path for the flow of charge. It will probably also contain.

Internal Resistance.

Chapter 8. Ohm’s Law  George Ohm experimented with circuits and came up with a mathematical relationship relating voltage, current and resistance in.

Electricity It’s Shocking!!. Current Electricity Current Electricity is a constant flow of electrons through a circuit. There are three main parts to.

CURRENT AND RESISTANCE LECTURE 8 DR. LOBNA MOHAMED ABOU EL-MAGD.

MOTOR VEHICLE ELECTRIC’S INTRODUCING OHM’S LAW BY PAUL LANE.

Emf and Internal Resistance To do Work in groups of 4 or 5 to carry out Activity 2 – Internal Resistance. Internal Resistance V In theory… V = 12 V In.

EMF and Internal Resistance Electricity Lesson 8.

Circuits. The Basics The Symbols Wire Resistor Light Bulb Plug Battery Open Switch Closed Switch Capacitor.

5.2.2 D.C. Circuits Practical circuits Electromotive force and internal resistance Kirchhoff’s laws Series and parallel arrangements Potential divider.

Internal Resistance E r The battery produces an electromotive force (emf), E, however the electrons loose some of this energy in travelling through it.

Internal Resistance. electromotive force revisited Remember the e.m.f.(ε) is the amount of energy given by the cell to each coulomb of charge passing.

ELECTROMOTIVE FORCE. Consider the following diagram showing a circuit with an external resistance (R) internal resistance (r) and EMF ( ε ). When.

Methods of Charging Conduction – A Charged Object comes in CONtact with a neutral object. – The neutral object takes on the same Net Charge as the Charged.

Electrical circuits P2 – part 2. Common components.

Series and Parallel Circuits SNC1D. Series and Parallel Circuits Key Question: How do series and parallel circuits work?

The Series Circuit Summary 1. The sum of the _____________or voltage equals the potential rise of the source. 2. The current is ______________ everywhere.

Bell Ringer 2/10 Write the objective

Internal Resistance and the EMF of a cell

Aim: How is a Series Circuit different from a Parallel Circuit?

Do Now: Why does current not come from a battery? Explain.

Calculate the current at point A

OHM’S LAW INTRODUCING MOTOR VEHICLE ELECTRIC’S BY PAUL LANE

ELECTROMOTIVE FORCE AND POTENTIAL DIFFERENCE

OHM’S LAW INTRODUCING MOTOR VEHICLE ELECTRIC’S BY PAUL LANE

Ch 35 Electric Circuits Electric Circuits.

E.M.F and Internal Resistance

Cfe Higher Physics Unit 3.2 Resistors in Circuits.

OHM’S LAW INTRODUCING MOTOR VEHICLE ELECTRIC’S BY PAUL LANE

Comparing Series and Parallel Circuits

Ohm’s Law – The relationship between Current, Voltage and Resistance.

Unit 1 Electricity Electric Fields and Potential Difference

High School Science Current, Voltage and Resistance

Unit 1 Electricity Electric Fields and Potential Difference

Electromotive Force Elliott.

Presentation transcript:

How We Load Power Supplies

All sources have an EMF. EMF is the open terminal voltage of the battery. All sources have a certain amount of internal resistance. Perfect batteries have 0 internal resistance. A car battery has very low internal resistance so is almost perfect

The car battery has a very low internal resistance. This means that it can give out the heavy current needed by a starter motor. You can see the heavy wires leading to the starter motor

V E V V R I This time we find that the terminal voltage goes down to V. It has been lost due to the internal resistance which heats the battery up. Emf = Useful volts + Lost volts In code: E = V + v

V E R I r The cell is now a perfect battery in series with an internal resistor, r. Internal resistance

o Emf = voltage across R + voltage across the internal resistance E = V +v o We also know from Ohms Law that V = IR and v = Ir, so we can write: E = IR + Ir E = I(R + r) or E = V + Ir

V E R I r o We adjust the variable resistor so we can record a range of voltages and currents. o We use the switch to avoid flattening the battery, and preventing the variable resistor from getting too hot. o We plot the results on a graph.

Current (A) P.d. (V) The graph is a straight line, of the form y = mx + c. We can make the equation for internal resistance V = -rI + E. There are three features on the graph that are useful: The intercept on the y-axis tells as the emf. The intercept on the x- axis tells us the maximum current the cell can deliver when the p.d. is zero, i.e. a dead short circuit. The negative gradient tells us the internal resistance.