As shown in figure "A" of the illustration,...

Question 1 of 270705eccefa3bacbc34ba4d47efb

As shown in figure "A" of the illustration, if the applied voltage is 12 volts DC, the resistance of R1 is 110 ohms, and R2 is 10 k ohms, what is the voltage measured across R1 when the switch is closed? See illustration EL-0020.

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Question 1 of 27070

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🔍 Key Concepts

• Series circuit behavior when the switch is closed (one path, same current through R1 and R2) • Using Ohm’s Law $V = I \times R$ and/or the voltage divider idea to find the voltage across one resistor in series • Converting kilo-ohms (kΩ) to ohms (Ω) before doing any calculations

💭 Think About

• When the switch is closed, how do R1 and R2 connect to the 12 V source in figure A—series or parallel? What does that tell you about the current through each resistor? • Once you know the total resistance, how can you find the circuit current, and then the voltage drop across just R1? • Alternatively, how can you use the ratio of R1 to the total resistance (R1 + R2) to directly find the share of the 12 V that appears across R1?

✅ Before You Answer

• Be sure you have converted R2 from kΩ to Ω correctly before adding it to R1. • Check that your total resistance and resulting current are reasonable for a 12 V DC circuit with a 10 kΩ resistor (the current should be quite small). • After you compute the voltage across R1, compare it with the answer choices and make sure the decimal point is in the right place—misplacing it will produce a value that is off by a factor of 10.