Electrical Circuit Questions.

[BarrettRC8]

I've been studying most of the material I've found on this site off and on for a month or so, and the only thing I don't understand is the electrical/battery type questions. I don't ever recall learning any of this in High School, and I haven't taken any classes at FSU that has hit on the basics of this. In an ASTB prep test I got from this site, the following questions are asked.

For questions 9, 10, and 11 refer to the diagram

9. If the current leaves the battery in the direction shown, what is the direction of the current in resistor X?
a. A
b. B
c. There is no current in the resistor

10. The voltage drop is greater across which resistor?
a. Rx
b. Ry
c. It is the same across either resistor

11. Where is the current greater in this circuit?
a. Greater at A then B
b. Greater at B then A
c. The same at A and B


Would someone please explain how to come to the conclusion of each answer? Thank you.

 

[TheBubba]

9. going from B to A. Think of a traffic circle. Flow is only in one direction.

10. Rx. The greater the resistance, the graeter the voltage drop.

11. c. there is no change in current. In a closed loop, there is nothing to reduce current.

I can't remember the equations, but hope it helps.

 

[The Chief]

9. going from B to A. Think of a traffic circle. Flow is only in one direction.
10. Rx. The greater the resistance, the graeter the voltage drop.
11. c. there is no change in current. In a closed loop, there is nothing to reduce current.
I can't remember the equations, but hope it helps.

Right answer, not sure of explanation re Q.11. This is a series circuit and in a series circuit, current flow is the same throughout the circuit.

OHM'S LAW FORMULA
When voltage is applied to an electrical circuit, current flows in the circuit.

The following special relationship exists among the voltage, current and resistance within the circuit: the size of the current that flows in a circuit varies in proportion to the voltage which is applied to the circuit, and in inverse proportion to the resistance through which it must pass. This relationship is called Ohm's law, and can be expressed as follows:

E = I R

Voltage = Current x Resistance

E Voltage applied to the circuit, in volts (V)
I Current flowing in the circuit, in amperes (A)

R Resistance in the circuit, in ohms

In practical terms "V = I x R" which means
"Voltage = Current (I) x Resistance (R)".

1 volt will push one amp through 1 ohm of resistance.

 

[The Chief]

Here is all you ever wanted to know about ohm's law!

 

[eddie]

See this thread:

http://www.airwarriors.com/forum/showthread.php?t=12506

 

[Steve Wilkins]

Good information here. You don't really need to do any calculations for this problem. You just need to understand basic electrical concepts.

 

[Fly Navy]

I hate using E for Volts. It stands for electrical potential (which is what a measurement of Volts is), but I'm still brainlocked on E meaning energy, as in Joules.

 

[Brett327]

Here is all you ever wanted to know about ohm's law!

The good ole, magic asshole.

Brett

 

[The Chief]

I hate using E for Volts. It stands for electrical potential (which is what a measurement of Volts is), but I'm still brainlocked on E meaning energy, as in Joules.

But it we must use E or otherwise the mnemonic "ELI the ICE man would not work":icon_tong :icon_tong :icon_tong

 

[Fly Navy]

But it we must use E or otherwise the mnemonic "ELI the ICE man would not work":icon_tong :icon_tong :icon_tong

I have an electrical engineering degree... and I have never seen that mnemonic ever... and I've been doing EE type stuff since junior year of high school. Explain? I like new things

 

[3RDMAW]

I have an electrical engineering degree... and I have never seen that mnemonic ever... and I've been doing EE type stuff since junior year of high school. Explain? I like new things

Its used to explain lead and lag of phase angles : voltage (E) lags current (I) in an Inductive circuit (L) while current (I) lags voltage (E) in a capacitive Circuit (C). Cut little trick they taught in Avionics years ago. Kind of like the Mnemonics for remembering resistor color code.

 

[The Chief]

Its used to explain lead and lag of phase angles : voltage (E) lags current (I) in an Inductive circuit (L) while current (I) lags voltage (E) in a capacitive Circuit (C). Cut little trick they taught in Avionics years ago. Kind of like the Mnemonics for remembering resistor color code.

Bingo, and the award goes to the Marines!

Fly; you are forgiven. It is more technician tool than engineering!!

Yes, resistor colour code:

Bad, boys, RESPECT, our, young, girls, but, violet, gives, willingly, sequenced 0 thru 9.

Black, brown, red, orange, yellow, green, blue, violet, grey, white?


((Needed to be PC))

 

[port_tack]

Yes, resistor colour code:

Bad, boys, RESPECT, our, young, girls, but, violet, gives, willingly, sequenced 0 thru 9.

I always liked:

Bad beer rots our young gut but vodka goes well.

 

[brd2881]

Dude...I was a EE major....I have unfortunately dumped quite a bit of what I learned....never came easy anyhow...
Meaning...I can't help you...:icon_smil

 

[Fly Navy]

Dude...I was a EE major....I have unfortunately dumped quite a bit of what I learned....never came easy anyhow...
Meaning...I can't help you...:icon_smil

I did a total brain dump too after graduating. I recently bought some of my old EE books to put on my bookshelf in case I ever want to refresh my brain (Sedra & Smith and Lathi)