# Find resistance in a circuit. (Circuit Analysis)

Status
Not open for further replies.

#### Shayaan_Mustafa

##### Full Member level 5
Hi experts!

Here are 4 components in the circuits,
${R }_{1 }$=47$\Omega$
${R }_{2 }$=?
${R }_{3 }$=33K$\Omega$
${V }_{1 }$220v

Given condition:
1mA of current is passing through the resistor ${R }_{2 }$.

Find the value of ${R }_{2 }$.

From where should I start. I just want a hint.

Thanks people.

#### Attachments

• Untitled.jpg
24.3 KB · Views: 16

#### keith1200rs

##### Super Moderator
Staff member
You need to generate several equations based on what you do know and then solve for them. So, you can write an equation for the voltage across R2 in terms of R2 & 1mA. That is also the voltage across R1 so you can write an equation for the current through R1. The current through R1 & R2 equals the current through R3. From that you can express the voltage across R3. the voltage across R3 and R2 add up to V1.

Keith.

johnwill

### johnwill

Points: 2

#### mister_rf

Start by using Kirchhoff's second law

I[(R1||R2) +R3]=220V
I – total current in circuit

I= I1 +I2
I1 current flowing through resistor R1
I2 current flowing through resistor R2
and
I1R1= I2R2

I2 = 1mA
R1= 47
R3=33K

johnwill

### johnwill

Points: 2

#### Shayaan_Mustafa

##### Full Member level 5
OK. Thanks for everyone.

I have made two equations having variables, R2 and I1.

Now its easy..

Thanks again.:-D

Status
Not open for further replies.

Replies
2
Views
2K
Replies
11
Views
5K
Replies
5
Views
2K
Replies
2
Views
1K
Replies
12
Views
1K