Calculating Current in a Series Circuit with an LED

[Marcin H]

Homework Statement

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.

 

[Jake 7174]

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?

 

[Marcin H]

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.

 

[cnh1995]

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?

 

[Marcin H]

Right. What is the voltage across resistor then?

Im not sure. Would it be 3V? Va-Vb?

 

[Jake 7174]

Im not sure. Would it be 3V? Va-Vb?

Good, Now, What is the current through the resistor

 

[Marcin H]

Good, Now, What is the current through the resistor

.01A. So does that mean that .01A are flowing through the LED?

 

[cnh1995]

.01A. So does that mean that .01A are flowing through the LED?

Yes.

 

[Jake 7174]

.01A. So does that mean that .01A are flowing through the LED?

In a series circuit is current constant?

 

[Marcin H]

In a series circuit is current constant?

Yes. same current, different voltage.

 

[Jake 7174]

Yes. same current, different voltage.

There you go. Good job!

 

[Marcin H]

There you go. Good job!

Thanks!