Review: 1. Electric field is defined as the aura about the space surrounding a charged object that exerts an electrical influence upon other charged objects in that space. The direction of the electric field vector is defined as the direction that a positive test charge would be accelerated. Potential energy is the energy stored in an object due to the position of that object. A Gravitational Analogy: Diagram A Diagram B 2. Two diagrams are shown at the right. In diagram A, a mass is held at an elevated position. When let go of, the A B mass falls from point A to point B. In diagram B, the mass is originally at point A and a person moves it back up to point B. For each diagram, indicate if work is done by a non-conservative force in B moving the object from its initial position (point A) to its position at point B. Finally, indicate the position of greatest gravitational potential energy. Wnc done on mass: Wnc done on mass: Circle the answers in the space below Yes or No Yes or No the diagrams. Highest PE: A or B Highest PE: A or B 3. The following diagrams show an electric field and two points - labeled A and B - located within the electric field. A positive test charge is shown at point A. For each diagram, indicate whether work must be done upon the charge to move it from point A to point B. Finally, indicate the point (A or B) with the greatest electric potential energy and the greatest electric potential (PE/charge). B. Work done on test charge? Yes or No Work done on test charge? Yes or No Potential energy is greatest at: A B Potential energy is greatest at: A B Electric potential is greatest at: A B Electric potential is greatest at: A B +B+Work done on test charge? Yes or No Work done on test charge? Yes or No Potential energy is greatest at: A B Potential energy is greatest at: A B Electric potential is greatest at: A B Electric potential is greatest at: A B When work is done on a positive test charge to move it from one location to I\1n the battery, energy is supplied to the charge to move it from low potential (- terminal) to high potential {+ terminal}. Once at the + terminal, the charge spontaneously moves through the external circuit, losing energy as it passes through each electrical device. The electric potential that is gained by the charge when it passes through the battery is lost by the charge as it moves through the external circuit. These gains and losses in electric potential are often represented using an electric potential diagram. For the circuit at the right, complete the electric potential diagram, showing the relative potential of locations A, B, C, D, E, and F. .n N '1' Potential c: f. MOP Connection: Electric Circuits: sublevel 1 1. To maintain a charge flow in an electric circuit, at least two requirements must be met: #1: An external energy supply [e.g., battery, wall outlet, generator, etc.) to pump the charge through the internal circuit and establish a potential difference across the circuit. #2: The external circuit must make up a "closed conducting loop" between the + and - terminal. Utilize your understanding of these requirements to state whether charge would flow through the following circuits. If there is no charge ow, then explain why not. Charge Flow: Yes or No? Charge Flow: Yes or No? Explanation: Explanation: Charge Flow: YES 01' N0? Charge Flow: Yes or No? Explanation: Explanation: Charge ow in a circuit is often compared to water flOw. For water to ow between two points, there must be a difference in water pressure between the points. Water pressure is like electric potential. Water will only flow through a pipe if there is a difference in potential between the two ends. Charge will only flow through a wire if there is an electric potential difference across its ends. Water won't flow if the two ends If the two ends of the pipe are at of the pipe are at the same potential. different potentials, then water will flow. 2. Consider the two requirements for an electric circuit (described in question #1). When a light bulb is burned out and no longer works, requirement #_ is not met. When a battery no longer works, requirement # is not met. 3. What do you believe? Respond to the following statements as being TRUE or FALSE. . When a battery no longer works, it is out of charge and must be re-charged T or F before it can be used again. b. A battery can be a source of charge in a circuit. The charge that flows through T or F the circuit originates in the battery. c. Charge becomes used up as it flows through a circuit. The amount of charge T or F that exits a light bulb is less than the amount that enters the light bulb. d. Charge flows through circuits at very high speeds. This explains why the light T or F bulb turns on immediately after the wall switch is flipped. e. Commonwealth Edison supplies millions and millions of electrons to our T or F homes every day. 4. A current is said to exist whenever. a. a wire is charged b. a battery is present c. electric charges are unbalanced d. electric charges move in a loop 5. As a quantity, electric current is defined as the a. amount of charge present in a circuit b. potential energy per charge c. rate at which charge moves through a cross-sectional area of a wire d. speed at which charge moves from one location to another location 6. Complete the statements: a. A current of one ampere is a flow of charge at the rate of coulomb per second. b. When a charge of 8 C flows past any point along a circuit in 2 seconds, the current is A. c. If 5 C of charge flow past point A (diagram at right) in 10 seconds, then the current is A. . If the current at point D is 2.0 A, then. C of charge flow past point D in 10 seconds. e. If 12 C of charge flow past point A in 3 seconds, then 8 C of charge will flow past point E in seconds. f. TRUE or FALSE: The current at point E is considerably less than the current at point A since charge is being used up in the light bulbs. 7. Which sentence best describes what happens to charge as it moves through an electric circuit?a. Charge is consumed or used up. 13. Charge is re-energized and recycled. 8. Which sentence best describes how fast charge moves through an electric circuit? a. Charge moves very fast, faster than any human can run. in. Charge moves very slowly, slower than the proverbial snail. 9. When you turn on the room lights, they light immediately This is best explained by the fact that a. electrons move very fast from the switch to the light bulb lament. b. electrons present everywhere in the circuit move instantly