Electricity and Magnetism Quiz True or False

1. Which of the following combinations of resistors will drain energy from a battery the fastest? -> 50 Ω and 50 Ω in parallel
2. What is the current through R1 ? Every resistor has a resistance of 100 Ω.
-> 48 mA
3. A thermocouple is a device that uses two welded together pieces of metal to create a voltage when exposed to a temperature change. A chromel-alumel thermocouple will produce a voltage of about 4 mV for every 100° of temperature difference it sees. In a room-temperature kitchen (20°), what current will be produced by a meat thermometer made of a thermocouple with an internal resistance of 10 mΩ when it's plunged into a 90° roasted chicken? -> 280 mA
4. A parallel plate capacitor is attached to a 7.2 V battery for several minutes, then disconnected. The distance between the plates of the capacitor is then halved and a wire is connected from one end to the other. What is the initial voltage seen on the wire immediately after the capacitor is reconnected? -> 3.6 V
5. Two inductors, one with L1 = 100 mH and one with L2 = 200 mH, are connected in series. L 1 has an internal resistance of 10 Ω, and L2 has an internal resistance of 20 Ω. When a voltage is applied to the circuit, what is the ratio of energy stored in L1 versus L2? -> 1/4
6. Two batteries labeled at 12 V—but with an internal resistance of 8 Ω—are connected in series. They are then both connected to a lamp consisting of three 100 Ω light bulbs wired in parallel. What is the current through each bulb? -> 162 mA
7. Batteries are often measures in amp-hours, a unit of charge where 1 Ah = 3600 C. This is, essentially, a way to measure how long a battery can provide a given current. If a 6.4 V battery rated at 700 mAh is attached to five 50 Ω light bulbs in series, about how long can the battery keep the lights on for? -> 27 hrs
8. How much energy can be stored in two parallel plate capacitors consisting of 0.01 m2 metal plates separated by 1 μm when they're attached in parallel to a 4 V battery? -> 2.83 μ J
9. What is the equivalent resistance of this six-resistor network? Every resistor is 1 kΩ.
-> 167 Ω
10. When a battery is attached to the resistor network in the previous question, what percent of the overall power dissipated is lost in R1 ? -> 62%

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