19.2 Resistance pp. 700 - 707 Mr. Richter. Agenda  Review HW  Chapter 19 Quiz Monday (second half)  Notes:  Resistance  Ohm’s Law  Human Resistance.

Slides:

Advertisements

Similar presentations

Voltage and Current How are electrical potential energy and gravitational potential energy similar? Just as a ball will roll downhill, a negative charge.

Advertisements

Current and Resistance FCI.  Define the current.  Understand the microscopic description of current.  Discuss the rat at which the power.

Electricity Chapter 34.

1 Chapter 27 Current and Resistance. 2 Electric Current Electric current is the rate of flow of charge through some region of space The SI unit of current.

Current, Resistance, and Simple Circuits.  A capacitor is a device used to store electrical energy.  There are two different ways to arrange circuit.

Current and Resistance

Electric Current and Ohm’s Law Chapter Key Concepts: – What are two types of current? – What are some examples of conductors and insulators? – What.

Electrical Resistance Gr 9 Science. 4 Electrical resistance = the property of a substance that hinders electric current and converts electrical energy.

ELECTRIC CURRENT Electricity, like water, can only flow if charged particles have potential.

Circuits & Electronics

Circuits Electric Circuit: a closed path along which charged particles move Electric Current: the rate at which a charge passes a given point in a circuit.

Voltage: the charge (electron) “pusher.” Voltage causes current to flow/move. Voltage sources: Battery Generator Outlets Symbol for voltage = V Unit for.

The “Live Action” Physics Review Game Topic: Circuits.

ElectricitySection 2 Voltage and Current 〉 How are electrical potential energy and gravitational potential energy similar? 〉 Just as a ball will roll downhill,

CHAPTER 7 ELECTRICITY BINGO. A circuit in which current has more than one path is called a _________________ circuit.

Making Sense of Circuits.  How much an object resists electricity flowing  Increasing resistance, lowers the current  Measured in Ohms (Ω)

Do Now What work is required to move 7 coulombs of charge through a potential difference of 3 volts?

Chapter 18 Electric Currents The Electric Battery Volta discovered that electricity could be created if dissimilar metals were connected by a conductive.

Nature of Electricity. Nature of Current Electricity To make things work  Need source 1.5 V cell has a limited life ( use it then throw it away) 240.

Chapter Twenty: Electric Circuits

Ch 19 Current and Potential Difference. Current is rate of charge movement: I = Δq/Δt. The unit of current is the ampere, or amp. 1A = 1C/s.

Chapter 27 Current and Resistance. Intro Up until now, our study of electricity has been focused Electrostatics (charges at equilibrium conditions). We.

Resistance and Ohm’s Law. Electron flow vs. Conventional current  There are two ways to explain the way current moves: Electron flow Conventional current.

UNIT V STUDY GUIDE Electricity & Magnetism

Electricity! Potential Difference, Current, Resistance, Ohm’s Law, Circuits.

Electric Current and Resistance Chapter 19 Sections 1 & 2.

Part 1 Current & Energy Transfer Electric Current.

 The continuous flow of electrons is current.  Measured in amps (A).  Two types of current 1. Direct current (DC) – electrons flow in only one direction.

Bellringer A standard household outlet has a voltage of what?

ELECTRIC CURRENT 2 Ohm’s law shows the relationship between current, potential, and voltage. We need a few more rules to make predictions about current.

Lecture 7 Electric Current Circuits Resistance and Ohms law Temperature variation Electrical energy.

Electrical Resistance Electrical resistance is a measure of how difficult it is for electricity (electrons) to flow through a material. The units of resistance.

Ohm’s Law and Resistance AP Physics C Montwood High School R. Casao.

Electric Current Flow of electric charges through a piece of material Amount of flow depends on material and the potential difference across the material.

Chapter 19 Review Current and Resistance. 1. A current of 2 amps flows for 30 seconds. How much charge is transferred?

Ohm’s Law Calculating Current, Voltage, and Resistance.

Electric Current Chapter 34 A charged object has charges with potential energy. A difference in potential energy causes the charges to flow from places.

Electric Currents. Electric Current Electric current is the rate of flow of charge through a conductor: Unit of electric current: the ampere, A. 1 A =

OHM’S LAW AND ELECTRICAL POWER. OHM’S LAW “Provided the physical conditions, such as temperature, are kept constant, the resistance is constant over a.

Ohm’s Law. Ohm’s Law states that the voltage v across a resistor is directly proportional to the current flowing through it.

7.2 Electric Current Current is the net movement of electric charges. – These can be electrons as in wires. – These can be ions as in electrolytes. In.

Electricity and Circuit. Types of Electricity Static Electricity – no motion of free charges Current Electricity – motion of free charges – Direct Current.

Current Resistance Electric Power & Energy. Voltage (V) Electric potential difference between 2 points on a conductor Sometimes described as “electric.

Electric Current Everything (water, heat, smells, …) flows from areas of high concentration to areas of lower concentration. Electricity is no different.

HOW FAST IS A NANOSECOND?. ONE-BILLIONTH OF A SECOND!!!

13.3 RESISTANCE & OHM’S LAW; PP Objectives: 1) Explain the relationships between current, voltage, and resistance 2)Use Ohm’s Law to calculate.

Physics Section 17.3 Apply the properties of electric current Electric current is the rate at which charge flows through a conductor. The charges can be.

The flow of charged particles charged particles ; through a conducting metal.

Base your answers to the question on the information below. A copper wire at 20°C has a length of 10.0 meters and a cross-sectional area of 1.00 × 10-3.

Measuring Electricity. Electric Potential – the electrical energy that an electron possesses. Electric current is a measure of the rate at which the electric.

Electric Fields and Potential. Electric Fields Every electric charge is surrounded by an electric field – the area around an electric charge where electric.

Reading Activity Questions? Objectives  By the end of this class you should be able to:  State the definition of electric current,  State the definition.

Ohm’s Law. Georg Simon Ohm born March 16, 1789, Erlangen, Bavaria [Germany]—died July 6, 1854, Munich German physicist who discovered the law, named after.

Current Electricity.

Electric Current Lesson 9.

Review of Calculations

Resistance in Circuits

Why Make Electrons Flow Anyway?

Ohm’s Law The relationship between voltage, current and resistance is known as Ohm’s Law: V = IR Voltage (V) = Current (I) x Resistance (R) Volts.

Electric Current and Electrical Energy

Electric Current.

Ohm’s Law This formula shows the relationship between current, voltage and resistance. Voltage (Volts) Current (Amps) Resistance (Ohms, )

Chapter 19-2: Pages Physics

Please bring your book tomorrow.

Ohm’s Law Page

Ohm’s Law & Circuits Chapter 7.2 & 7.3.

Voltage Difference The difference in electrical potential between two places. Unit of measure = V (volts) Voltage causes current to flow through an electric.

Electric Current Chapter 34.

Presentation transcript:

19.2 Resistance pp Mr. Richter

Agenda  Review HW  Chapter 19 Quiz Monday (second half)  Notes:  Resistance  Ohm’s Law  Human Resistance  Resistors and Superconductors

Objectives: We Will Be Able To…  Understand the relationship between resistance, current and voltage.  Calculate using Ohm’s Law.  Know what factors affect resistance.  Define resistors and superconductors.

Warm-Up:  If current is like water flowing in a river, what do you think resistance is?

Resistance

 What does resistance mean?  Resistance is the measure of how strongly an object inhibits the flow of electric current.  High resistance = low current, few electrons flow  Low resistance = high current, many electrons flow.

Resistance  Every device that uses electrical energy adds to the total resistance to a circuit.  The more total resistance the circuit has, the less the current.

Resistance  Remember, electron flow is bumpy and indirect.  The resistance of a material largely depends on (p. 701):  length  cross-sectional area  type of material  temperature

Ohm’s Law

 The resistance (R) of a material is the ratio of the applied voltage to the current that flows through.  This ratio is known as Ohm’s Law:  Resistance is measured in Ohms [ Ω ] A.K.A.: V = IR

Ohm’s Law: Relationships  Voltage and current are directly proportional.  With constant resistance  Resistance and current are inversely proportional.  With constant voltage. A.K.A.: V = IR

Human Resistance

 Why will a 9-volt battery not shock you on your arm, but shock your tongue?  Human skin usually has a resistance of approximately 500,000 Ω.  A 9-volt battery creates a current of about 9/500,000 or ~1.8 x A ( A)  Humans only feel current at about 0.01 A

Human Resistance  The resistance of wet skin can decrease to as little as 1000 Ω or even 100 Ω, or about 1000 times less resistance.  Water, and especially salt water, creates a better conductor.  Lots of free electrons!  This creates as much as 0.09 amps of current.  This is enough for human nerves to sense. And hurt.

Resistors and Superconductors

Resistors  Resistors can be used to control the flow of current in a circuit.  Current can also be controlled by adjusting voltage, but voltage is usually constant (like a 120-volt outlet)  A resistor is an element that provides a specified resistance.

Superconductors  Superconductors have no resistance below a critical temperature, usually near absolute zero.  Weird stuff: once current is established, it can continue even when the potential difference is removed.  This can create semi-permanent electromagnets, and super-efficient electric circuits.

Wrap-Up: Did we meet our objectives?  Understand the relationship between resistance, current and voltage.  Calculate using Ohm’s Law.  Know what factors affect resistance.  Define resistors and superconductors.

Homework  p707 #1-5, 7