Parallel/series, calculate current drawn

  • Thread starter Thread starter mikefitz
  • Start date Start date
  • Tags Tags
    Current
AI Thread Summary
The discussion focuses on calculating the current drawn in a circuit with multiple resistors. The initial calculations incorrectly treated all resistors as series when some were actually in parallel. The correct approach involves simplifying the circuit by recognizing that two 30K ohm resistors are in parallel, as well as the 40K and 66.7K ohm resistors. After recalculating, the total resistance is found to be approximately 69,375.5 ohms, leading to a corrected current of about 0.000144A. The importance of correctly identifying resistor configurations is emphasized for accurate calculations.
mikefitz
Messages
155
Reaction score
0

Homework Statement


http://img267.imageshack.us/img267/8159/untitled3ct1.gif

Find the current drawn.

Homework Equations



V=IR
R1+R2+Rn
1/ (1/R1)+(1/R2)+(1/R3)+(1/R4)

The Attempt at a Solution



R1=20,000ohms
R2=70,000ohms
R3=96,7000ohms
R4=40,000ohms

1/ (1/R1)+(1/R2)+(1/R3)+(1/R4) = 10037.44

10=I(10037.44)
I=.000996A

Where did I go wrong?
 
Last edited by a moderator:
Physics news on Phys.org
Think of the two 30Kohm resistors as being in parallel. Also, think of the 40 and 66.7 kohm resistors as being in parallel. Now, you have simplified that whole middle section into two resistors in series. you can go from here.
 
Simple error, the 30K resistors are in parallel, as are the 40K and 66.7. These in turn are in series and that resultant in parallel with the other two branches.
 
r1=20,000
r2=15,000
r3=25,004.7
r4=40,000

r2&r3 in parallel= 9,375.5

20,000+9,375.7+40,000=69,375.5

10=I(69,375.7)

I=.000144A ??
 
Almost R2 and R3 are in series.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Total equivalent resistance of a combined circuit
Replies
7
Views
2K
Calculate the equivalent resistance
Replies
11
Views
2K
Platinum resistance thermometer and Kirchoff's Laws
Replies
1
Views
3K
How Do You Calculate Total Resistance in Mixed Resistor Circuits?
Replies
14
Views
2K
Voltage, Current, and Resistance Calculations
Replies
13
Views
2K
Finding the Current in a Resistor in a Closed Circuit
Replies
4
Views
2K
How to determine the power of this circuit?
Replies
2
Views
1K
Solving series-parallel circuits
Replies
1
Views
1K
Arrange bulbs in descending order of brightness
Replies
3
Views
2K
Finding the current and voltage for each resistor
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top