DC Circuit with 4 Resistors Need help on #4 I have the first three figured out a

Question

DC Circuit with 4 Resistors

Need help on #4

I have the first three figured out and correct but am having a brain fart on the last one. Please Help. Thanks.

R1 = 3 ohms, R2=5 ohms, R3 = 11 ohms, R4 = 8 ohms, and V= 4V

1.What is the current through resister R1?

Correct answer is 1.33 A

I got this 4V = I1(3)

2. What single, equivalent resistor could replace all of the resistors in this circuit?

Correct answer is 2.47 ohms.

I got this via (1/R24) = (1/R2) +(1/R4) then adding the result to R3 to get R234. Then (1/Rtotal) = (1/R) + (1/R234)

3. What is the current supplied by the battery?

Correct answer is 1.62 A

I got this via V = I total x R total. 4 = I total x 2.47

4. What is the current through the resistor R2?

________________ A

Explanation / Answer

a)

Current through R1 is

I1=V/R1=4/3 =1.33 A

b)

equivalent resistance

R2 and R4 are in parallel

1/R24=1/5+1/8

R24=3.08 ohms

R24 is in series with R3 ,so

R234=R3+R24=3.08+11=14.08 ohms

R1 and R234 are in parallel

1/Req =1/R1 +1/R234=1/14.08 +1/3

Req=2.47 ohms

c)

Current through battery is

IB=V/Req=4/2.47=1.62 A

d)

Current through R3 is

I3=Ib-I1=1.62-1.33 =0.29 A

Current through R2 is

I2=I3*(R4/R2+R4) =0.29*(8/8+5)

I2=0.18 A

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