1. How is electrical current dened? How is the current related to the average drift velocity of electrons? 2. A student has questions regarding the cause for electrical current in a wire. Give a reasonable response for the following questions: a. If a wire is hooked up to a 9V battery, then the potential difference from one end of the wire to the other is 9V. This means that an electric eld exists in the wire but I thought that the electric eld inside a metal is zero. .? b. Ok, then if there is an electric eld, then there is a force on the charges throughout the wire, meaning they should be accelerating do the charges just keep on accelerating until they slam back into the battery? 3. Consider the analogy for the ow of electrical current where the charge moves like water owing in a pipe system. In the following parts, give a thorough description of how each electrical element might be thought of in terms water owing through pipes. a. The electrical current is the total charge owing per second. What is the current in the water analogy? (Distinguish this from the speed of the owing water) b. A resistor provides friction, slowing the ow of electrons. What might a resistor be in the water analogy? c. The voltage is dened all the way around the circuit and pushes the current through the resistors. What might the voltage be in the water analogy? d. A battery provides a jump in voltage, providing the energy to drive the current through the circuit. What might the battery be in the water analogy? 4. What is the difference between resistance and resistivity? Write down the relevant equations for resistance and resistivity. 5. Answer Concept Questions #7 and #8 regarding the lightbulb brightness in different congurations. Hint: The brightness of a lightbulb depends on the current owing through the lightbulb. Consider Kirchhoffs loop rule and Kirchhoffsjunction rule. 7. Both batteries in FIGURE Q27.7 are ideal and identical, and all light- bulbs are the same. Rank in order, from brightest to least bright. the brightness of bulbs a to c. Explain.000 FIGURE Q27.7 8. Both batteries in FIGURE Q27.8 are ideal and identical, and all lightbulbs are the same. Rank in order, from brightest to least bright, the brightness of bulbs a to c. Explain. FIGURE Q27.8