Calculating Current in a Series Circuit with an LED

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In a series circuit with a 300-ohm resistor and an LED, the current is the same throughout the circuit. The initial calculation of current using 5V across the resistor was incorrect, as the voltage across the resistor is actually 3V after accounting for the LED's 2V drop. The correct current through the resistor and LED is 0.01A. Understanding that in a series circuit, the current remains constant while the voltage varies is crucial. This clarification helped resolve the initial confusion regarding the circuit's behavior.
Marcin H
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Homework Statement


Screen Shot 2016-02-04 at 11.54.34 AM.png


Homework Equations


V=IR

The Attempt at a Solution


I'm not sure if this is right, but I did this problem by finding the current in the 300ohm resistor by doing I=5V/300ohms = .0166A and since they are in series they have the same current. I don't think that is right though. The LED is 2V, so I'm not sure how to treat that.
 
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Marcin H said:

Homework Statement


View attachment 95288

Homework Equations


V=IR

The Attempt at a Solution


I'm not sure if this is right, but I did this problem by finding the current in the 300ohm resistor by doing I=5V/300ohms = .0166A and since they are in series they have the same current. I don't think that is right though. The LED is 2V, so I'm not sure how to treat that.

The voltage across the resistor is not 5 v. What type of circuit is this (series / parallel). What do you know about the voltage and current in that type of circuit?
 
Jake 7174 said:
The voltage across the resistor is not 5 v. What type of circuit is this (series / parallel). What do you know about the voltage and current in that type of circuit?
It's a series circuit right? In series current is the same throughout the circuit and voltage is different. For parallel voltage is the same and current is different.
 
Marcin H said:
It's a series circuit right? In series current is the same throughout the circuit and voltage is different. For parallel voltage is the same and current is different.
Right. What is the voltage across resistor then?
 
cnh1995 said:
Right. What is the voltage across resistor then?
Im not sure. Would it be 3V? Va-Vb?
 
Marcin H said:
Im not sure. Would it be 3V? Va-Vb?

Good, Now, What is the current through the resistor
 
Jake 7174 said:
Good, Now, What is the current through the resistor
.01A. So does that mean that .01A are flowing through the LED?
 
Marcin H said:
.01A. So does that mean that .01A are flowing through the LED?
Yes.
 
Marcin H said:
.01A. So does that mean that .01A are flowing through the LED?

In a series circuit is current constant?
 
  • #10
Jake 7174 said:
In a series circuit is current constant?
Yes. same current, different voltage.
 
  • #11
Marcin H said:
Yes. same current, different voltage.

There you go. Good job!
 
  • #12
Jake 7174 said:
There you go. Good job!
Thanks!
 

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