Section 1 review
Electric current is the flow of electric charge through a material such as a conducting wire. Electric current flows in response to differences in electrical potential, or voltage. A battery uses chemical potential energy to generate a voltage, which can cause electric current to flow in a conductor. A closed circuit provides at least one complete conducting path for current to travel in a closed loop. An open circuit, such as a flashlight that has been turned off, contains a break in the conducting path and so does not enable current to flow. Circuits must contain a voltage source and can also contain components such as light bulbs, resistors, and switches. Read the text aloud
electricity, electric current, ampere (A), electric circuit, open circuit, closed circuit, electrical symbol, short circuit, volt (V), potential difference, voltage, voltmeter, battery

Review problems and questions

  1. One mole of electrons is approximately 6.0×1023 electrons (that’s six hundred billion trillion electrons). The ampere is the SI unit of electric current, but we could also measure current in moles of electrons per second. How many amperes equal one mole of electrons per second? Read the text aloud Show
  1. Portable electronic devices such as cellphones and media players have rechargeable batteries. When a battery is fully charged this means that it contains its maximum energy, which it can then supply to the electric charges that pass through it. The energy a battery provides is often stated in units of milliampere-hours, or mAh (based on its voltage). Suppose that your media player is rated at 100 mAh.
    1. How many electrons does 100 mAh represent?
    2. Suppose that you can listen to 5 hr of continuous music on this device after fully charging its battery. What is the average current in milliamperes (mA) that flows through the device while you listen to it? Read the text aloud Show
Open, closed, and short circuits
  1. Identify each of the circuits shown above as a closed circuit, an open circuit, or a short circuit. Each term is used only once. Read the text aloud Show
Circuit diagram for a simple flashlight
  1. This circuit diagram for a simple flashlight shows the direction of current flow, as conventionally defined. It also shows the positive and negative terminals of the battery. What is the relationship between electron flow and the arrowed current shown here? Read the text aloud Show
  1. A student constructed a one-lamp circuit placing both ends of the lamp socket into the middle holes of row 11 of a circuit breadboard. He then connected a battery to the circuit using wires placed into holes on the two ends of row 11. Will his circuit work? Why or why not? Show
  1. A student has two batteries to dispose of, one alkaline and the other NiCd.
    1. Are either or both of the batteries considered hazardous waste?
    2. What is the procedure for disposing of each?

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