Stuck on question about resistance

Hi all, i am relatively new to electronics, i have always had an interest but never studied it, now at 46 I am taking the leap!!! I am reading a book and have come to the end of a specific chapter on resistance, there are questions at the end that I have managed to answer but the last 2 have really stumped me, and i was hoping someone here could help. The first question is: Take a look at the following diagram, if the voltage drop between Point B and C is 2v and the voltage drop between C and D is 3v, what is the Voltage drop between A and E? What is the voltage at Point A and Point E

2nd question: If that circuit runs with 2A total current what is the value of the resistor R1

This has had me perplexed for days now, Any help would be greatly received.

by Ericobi
July 21, 2023

3 Answers

Answer by jbowler12345

To answer your first question, when two resistors are in series like R3 and R4 they share the same current, and when resistors are in parallel like R2 and R3&4 they share the same voltage. With that in mind, since the voltage across both R3 and R4 adds up to 5V and R2 is in parallel, R2 shares the same 5V.

To answer your second question, you know that the total voltage drop across all R2, R3, & R4 is 5V and the supply is 9V, so the voltage across R1 is 9V - 5V = 4V. Ohms law states that V = I*R and therefore R = V/I = 4V/2A = 2Ohms.

The remaining resistances can be found by the current being split evenly between R2 and R3&4 and using the known voltages with ohms law.

+1 vote
by jbowler12345
July 27, 2023

Answer by alicentjenner

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+1 vote
by alicentjenner
August 07, 2023

Answer by weberralph

Great that you're learning electronics! Let me see if I can help with these circuit questions:

For the first one, we know: drift hunters - Voltage drop BC = 2V - Voltage drop CD = 3V Since those drops are in series, the total voltage drop from A to E is their sum:

  • Voltage drop AE = Voltage BC + Voltage CD = 2V + 3V = 5V

We don't know the actual voltage at points A or E, but we know the difference between them is 5V.

+1 vote
by weberralph
September 05, 2023

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