What would be the new current (in terms of I) if the voltage is doubled and the same resistance is used?

Transcription

1 Test Name: Electricity Unit Test Test Id: Date: 12/15/2015 Section Which of the following statements correctly describes the relationship between current (measured in amperes), resistance (measured in ohms), and voltage (measured in volts) in a circuit? 1. The current is equal to the voltage divided by the resistance. The resistance is equal to the current divided by the voltage. The current is equal to the voltage multiplied by the resistance. The resistance is equal to the current multiplied by the voltage. A resistor with a resistance of R is connected to a battery with a voltage of V to produce a current of I. What would be the new current (in terms of I) if five times the voltage and one-third the resistance is used? 2. The new current will be ½ I. The new current will be 2 times I. The new current will be 8 times I. The new current will be 15 times I. A resistor with a resistance of R is connected to a battery with a voltage of V to produce a current of I. What would be the new current (in terms of I) if the voltage is doubled and the same resistance is used? 3. the current will not change the current will be cut in half the current will be twice as much the current will be four times as much Ohm's Law states voltage equals current times resistance. When the voltage in a circuit is held constant, what is the mathematical relationship between the resistance and the current in the circuit? Page 1

2 4. proportional non-proportional directly proportional inversely proportional Directions: The graph below represents data obtained by applying varying potential differences to a metallic conductor at a constant temperature. Use the graph to answer any questions that follow. At 6.0 volts, what is the rate of energy use by the conductor? W 12 W 18 W 54 W The circuit diagram below represents four resistors connected to a 12-volt source. What is the total current in the circuit? Page 2

3 A 2.0 A 8.6 A 24 A A 5-ohm and a 10-ohm resistor are connected in series. The current in the 5-ohm resistor is 2 amperes. What is the current in the 10-ohm resistor? A 1 A 2 A 8 A The diagram below shows a circuit with three resistors. What is the resistance of resistor R 3? ohms 4.0 ohms 6.0 ohms 12 ohms Emilia walks out of her classroom into the bright sunshine. She glances at the hot sun as she touches the cement wall of her classroom. The cement wall feels very warm when she touches it. Which of the following sequences correctly describes the transfer of the sun s energy to Emilia s finger? Page 3

4 9. potential energy to electrical energy to light energy to heat energy nuclear energy to electromagnetic energy to heat energy to kinetic energy nuclear energy to electromagnetic energy to kinetic energy to thermal energy potential energy to heat energy to kinetic energy to electromagnetic energy The diagram below illustrates a ball rolling down a hill at four different points. The ball at point A has 100 Joules of potential energy. As the ball rolls down the hill, what is the first illustrated point at which the kinetic energy would be greater than the potential energy? 10. A B C D What energy transformation occurs during the process of photosynthesis? 11. chemical to heat chemical to kinetic heat to chemical radiant to chemical Page 4

5 According to the law of conservation of energy, which of the following is true? I. Energy is not conserved. II. Energy cannot be created or destroyed. III. Energy can transfer from one form to another. 12. I only II and III I and III I, II, and III A toy robot runs on batteries and is operated by a remote control. The robot is made to walk in a circle and then talk. What type of energy transformations occur during this process? 13. kinetic energy to heat energy to sound energy nuclear energy to kinetic energy to sound energy thermal energy to potential energy to sound energy chemical potential energy to kinetic energy to sound energy A ball is thrown up into the air. When it reaches its highest point, it has 100 J of potential energy. When it returns to the point from which it was thrown, it will have how much kinetic energy? 14. a little less than 100 Joules of kinetic energy exactly 100 joules of kinetic energy a little more than 100 joules of kinetic energy much more than 100 Joules of kinetic energy Page 5

6 What energy transformation occurs when a firecracker explodes? 15. chemical to light and sound electrical to sound and kinetic kinetic to potential and light mechanical to electrical and light Manuela investigated the usefulness of several materials to serve as wires in a circuit. Her results are in the table above. Which of the materials tested is best described as an "insulator"? 16. material A material B material C material D Using the following information, which grouping would be considered conductors? Group 1: copper, pure water, glass Group 2: plastic, diamond, lead Group 3: wood, silicon, concrete Group 4: aluminum, dirty water, brass Page 6

7 17. Group 1 Group 2 Group 3 Group 4 Which of the following statements is true about metal in terms of electron movement and insulation or counduction capacity? 18. The electrons in metal move easily throughout the material, making it a conductor. The electrons in metal do not move easily throughout the material, making it a conductor. The electrons in metal move easily throughout the material when it is at low temperatures but do not move easily when it is at high temperatures, making it a semi-conductor. The electrons in metal move easily throughout the material when it is at high temperatures, but do not move easily when it is at low temperatures, making it a semiconductor. Which of the following elements would be the best conductor for electricity? 19. brass copper neon sodium chloride Which of the following statements is true about plastic in terms of electron movement and insulation or counduction capacity? Page 7

8 20. The electrons in plastic move easily throughout the material, making it an insulator. The electrons in plastic do not move easily throughout the material, making it an insulator. The electrons in plastic move easily throughout the material when it is at low temperatures but do not move easily when it is at high temperatures, making it a semiconductor. The electrons in plastic move easily throughout the material when it is at high temperatures, but do not move easily when it is at low temperatures, making it a semiconductor. When Sammy plugs in his laptop to recharge the battery, he notices that he can safely handle the electrical cord. Why is he able to hold the cord without feeling the electrical current moving through it? 21. The electrical current transfers the charge through the metal wire. The electrical current does not move freely through the metal wire. The plastic surrounding the metal wire insulates the electrical charge. The plastic conducts the electrical charge inward towards the metal wire. Page 8