EK Physics 1001Qs #830 Circuits

[vashka]

Advertisement - Members don't see this ad

I apparently don't understand circuits with more than one loop. The answer says that resistors f and g are in series but their combination is in parallel with resistor c. Can someone explain this? The same issue comes up again in question where resistors d and f are in parallel but their combination is in series with resistor g. Pls help if you can, thanks.

 

[Jepstein30]

I apparently don't understand circuits with more than one loop. The answer says that resistors f and g are in series but their combination is in parallel with resistor c. Can someone explain this? The same issue comes up again in question where resistors d and f are in parallel but their combination is in series with resistor g. Pls help if you can, thanks.

Do you recognize what "series" and "parallel" is on a circuit?

If you do, you want to break down each circuit part by part. Replace a resistor in series/parallel with an equivalent resistor.

Would be easier if you could post a picture of the problem but with the info you gave:

f and g are in series.. replace this with resistor A

Resistance of A is f + g.

Now, A is in parallel with resistor c. Let's combine these two into resistor B.

1/ Resistance of B = 1/A + 1/c

etc. etc.

 

[vashka]

I hope this attachment works.

 

[Jepstein30]

I hope this attachment works.

That's a pretty difficult circuit I doubt the MCAT will ask about.

So the strategy is to combine components as you go around the circuit.

as long as there are no wires going in multiple paths in between resistors, you can combine them. For instance, you can't combine resistors b and d because you have alternate paths, they aren't in series with eachother.

Start from the battery and work our way around:

Resistors a and b are in series. Replace this with resistor Z with total resistance a + b = 6 ohms.

Redraw the picture so you have now one resistor instead of a and b.

See where else you can combine resistors and keep re-drawing, etc.

WIth the switches thrown in, thats a little more difficult and honestly, I doubt the MCAT ever throws in anything but a simple circuit.

 

[sciencebooks]

That's a pretty difficult circuit I doubt the MCAT will ask about.

So the strategy is to combine components as you go around the circuit.

as long as there are no wires going in multiple paths in between resistors, you can combine them. For instance, you can't combine resistors b and d because you have alternate paths, they aren't in series with eachother.

Start from the battery and work our way around:

Resistors a and b are in series. Replace this with resistor Z with total resistance a + b = 6 ohms.

Redraw the picture so you have now one resistor instead of a and b.

See where else you can combine resistors and keep re-drawing, etc.

WIth the switches thrown in, thats a little more difficult and honestly, I doubt the MCAT ever throws in anything but a simple circuit.

I agree, I also don't think I've seen anything where you had to solve for the circuit with switches. Rather they might test it conceptually? Like if ___ switch was closed, what would happen to ___?

 

[Jepstein30]

I agree, I also don't think I've seen anything where you had to solve for the circuit with switches. Rather they might test it conceptually? Like if ___ switch was closed, what would happen to ___?

Even then, switches gets pretty complicated. I mean, I've seen switches with capacitors just relating to simple charge/discharge but nothing like that.

The official topic list from AAMC doesn't really mention switches explicitly either.