What is the shortcut on solving problems that deal with ohms law?
You'll have to be more specific.
I | R
Here is a pyramid so if you want to solve for eg; E = IR. Just cover up what you want to solve for and the remaining letters left are your formulas. Another eg; I = E/R. Is that what you mean, sir? Does that help?
ok well i have problems here that im done with already. dealing with the calculating the current.
used these kind of formulas:
resistance = voltage/current
current = voltage/resistance
now i was asking if there was easier shortcuts on solving these.
now looking at the last problem i am stuck. instead of asking for ohms or amps it asked find the current of a watt.
calculate the current in a 140-w electric blanket connected to a 120-v outlet
now my question is how to solve that with a diffrent formula? what formula is this?
That's not short enough for you? [?]
You need to learn basic units, and you need to start reading your book. I am not going to tell you the formula, because that gives away the whole thing. I am going to ask you a couple of questions that will lead you to the answer.
1. What quantity is measured in Watts?
2. Is there a formula in your book that relates the quantity in #1 to current (answer: YES, there is).
The pyramid is "V" on top, with "I" and "R" on the bottom. It can be expressed as three complimentary equations:
1) Voltage = Current * Resistance.
2) Current = Voltage / Resistance.
3) Resistance = Voltage / Current.
Any time you have two of the factors from one side of the equation, you will know the third factor (the other side). In your question "calculate the current in a 140-w electric blanket connected to a 120-v outlet", you have Watts and voltage.
Now you need to figure out what the "Watts" means. Watts is volts*amps. Again, you can draw a pyramid to help remember it all. Put Watts at the top, and across the bottom you have volts and amps (amps being current). Again, this allows three expressions:
1) Watts = Voltage * Current.
2) Current = Watts / Voltage.
3) Voltage = Watts / Current.
Now, Watts is voltage*amps. Since you know the Watts and voltage, you can divide Watts by voltage to get current. 140/120 = 1.15 Amps, roughly.
Now you have two factors necessary for working with Ohm's Law. You have the voltage (120) and the current (1.15).
The short version:
Watts = voltage*amps.
You've got voltage and watts: watts (140) = volts (120) * ?.
So, by re-arranging the factors you can get: ? = watts (140) / voltage (120).
Simply fill in the "?".
remember P=IE, my friend.
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