Section 2 review
Ohm’s law states that the current I through a conductor is the voltage drop V divided by resistance R (or, in other words, I = V/R). The SI unit for resistance is the ohm, abbreviated Ω. Conductors are materials that offer little resistance to current flow when subjected to a voltage. Insulators are materials that strongly resist current flow. Resistors are used in electric circuits to control current flow. Engineers design the resistance of electrical devices to draw the right current when connected to the right voltage. Read the text aloud
Ohm’s law, ohm (Ω), resistance, resistor, digital multimeter, electrical conductor, electrical insulator

I= V R

Review problems and questions

Simple closed circuit
  1. A resistor and voltage source are connected in a simple closed circuit, as shown here. The resistor obeys Ohm’s law.
    1. If the voltage V doubles but resistance stays the same, what happens to the current I?
    2. If the resistance R doubles but the voltage remains unchanged, what happens to the current? Read the text aloud Show
Which carries a larger current?
  1. Two simple closed circuits are shown. Which carries a larger amount of current?
    1. A carries a larger current than B.
    2. A carries a smaller current than B.
    3. A and B carry equal amounts of current.
    4. You cannot tell without more information. Read the text aloud Show
  1. Which of these is the correct equivalent to an ohm (Ω) ?
    1. V/A
    2. A/V
    3. V A
    4. V A2
    5. A2/V Read the text aloud Show
  1. A child coats the “top” (+ end) of a flashlight battery with thick shiny paint. He allows the paint to dry. He then inserts the battery into his flashlight and slides the switch to the “on” position. The bulb immediately gives off light. What can we conclude about the paint?
    1. The paint is an insulator.
    2. The paint contains free (mobile) electrons.
    3. The paint contains flakes of copper. Read the text aloud Show

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