what is the formula for voltage?
368244
V (Voltage) = I (Current) x R (Resistance)\n\nOr (although you probably don't need it):\n\nJ (current density) = sigma (conductivity) x E (electric field)\n\nI always use wikipedia to look up stuff like this, it's very helpful for all kinds of info.
732893
we know that for power, P=IV. we also know that whatever power goes into the transformer comes out of the transformer(conservation of energy). this means that V is inversely proportional to I. or I is inversely proportional to V.\n\nif you already know how much V was stepped up, then just step down the I by the same ratio. for eg, if 110V 10A was transformed to 220V, then the step up ratio is 2. therefore current is stepped down by 2. so current will be 5. try equating 110x10 with 220x5, it is constant.\n\nall of this assumes that the transformer is 100% efficient. if there are losses due to heat, then you multiply the exit current by the efficiency factor. eg, if the trans is said to be 80% effiecient, then the actual exit current would not be 5A but 4A. voltage is not affected by effiency issues.\n\nby the way transformers only work with AC, the guy who mentioned direct currents is thinking of current rectifer not transformer.
472581
The equation for this is relatively simple.\n\nVp/Vs = Np/Ns\n\nWhere: \nVp=Voltage primary winding.\nVs=Voltage secondary winding.\nNp=Number of coil turns on the primary winding.\nNs=Number of coil turns on the secondary winding.\n\nThus taking that into consideration you should be able to get the voltage for both sides.  To get the current on both sides.  Just realize that you need the resistance.\nOr if you have the current on one side, use the conservation of Power equation:\n\nVpIp=VsIs\n\nWhere: \nVp=Voltage primary winding.\nVs=Voltage secondary winding.\nIp=Current in the primary winding.\nIs=Current in the secondary winding.
724085
Its substitution.\n\nYou are given p=i*v\n\nand you need to express it in terms of one variable using ohms law v=i*r\n\nYou want p, so you need to trade out either the i or the v from p=i*v\n\nif you trade out the v using ohms law as (i*r) then your power equation becomes p=i*(i*r) = i^2 *r\n\nif you trade out the i using ohms law, first you solve for i getting i=v/r then substitute into the p-equation.  \nThe substitution yields p=(v/r)*v  = v^2 /r\n\nThis is straightforward algebra.
679488
simple use two resistors, 6 and 3k ohm , in series and take the volatage across the 3 ohm resistor, it will be 3V.....\n\nuse the laws,\n\nif you have a voltage source, and two resistors p and q in series with it, \n\nthe voltage across p is given by  Vx(p/(p+q)), here u know voltage across p(Vp)= 3V, or 4.7 V or whatever....\n\nso, Vp = V x p/(p+q)....\n\nu know the value Vp, and V so substitute them......\n\n3 = 9 x p/(p+q)\n\nso p + q = 3p, \n\nso "2p = q", take two resistors ( in kilo ohms, coz u cant use just ohms, coz they are very large) such that one is double the value of other.......\n\nand connect the circuit across the 'p' resistor......\n\nwith 4.7, u get,\n\n4.7 = 9 x p/(p+q).....solve ...and choose resistors accordingly
568661
Let's see if I can remember...\n\na) Find the current flowing through a DC circuit, from a 12V battery and a 3 ohm resistor.\n\nBy Ohm's Law, V = IR, where\n\nResistance = ohms = R\nCurrent = amperes = I\nVoltage = volts = V\n \nYou want to find the current, in amperes, so we switch the equation around a little: if V = IR, that also means that I = V/R (dividing both sides by the same thing gives the same answer).\n\nNow, plug in our values:\nI = (12 volts/ 3 ohms) = 4 amperes\n\nb) what is the current in an AC circuit, with 120 V and 60 W lightbulb.\nIn this case, Watts is a unit of power, and volts is a unit of resistance, and amperes is a unit of current. Electrical power is amperes times volts, or W = I * V\n\nIn this case, W = 60 and V = 120, so we rearrange it:\nW = I * V or \nI = W/V or \nI = (60 watts/120 volts) = 0.5 A\n\nAs for the atom model problem...hmmm! Si is the symbol for silicon. It has an atomic number of 14 (not 16) and an atomic mass of 28.085. According to the Bohr model of an atom, every atom has electrons (with no mass, and a negative charge), protons (with a mass, and a positive charge) and neutrons (with a mass, and no charge). The number of protons and electrons must be equal in order for the atom to have no charge, if one is greater than the other, it results in an ion (positive ion if protons are greater than electrons, negative ion if electrons are greater than protons). Electrons orbit around a nucleus of protons and neutrons.\n\nNow, an element's atomic number (14 in this case) is the same as the number of protons (and electrons, since the element is not an ion, in this case). So a silicon atom has 14 electrons orbiting around its nucleus, and its nucleus also has 14 protons and a number of neutrons.\n\nThe electrons orbit in shells around the nucleus. In the case of silicon, the inner shell has two electrons, the next shell has the maximum number possible or eight, and the third shell has the other electrons, or four. (To check, 2+8+4 = 14.) \n\nFinally, the number of neutrons in the nucleus can be calculated if we know how much a neutron weighs and how much a proton weighs. If N is the weight of a neutron, and P is the weight of a proton, and the number of neutrons is n1, and the number of protons is n2, and we say that the atomic weight is A, we have:\n\nA = (n1 * N) + (n2 * P)\n\nWe want to find n1, so we rearrange this like:\n(n1 * N) + (n2 * P) = A\n(n1 * N) = A - (n2 * P)\nn1 = (A - (n2 * P))/N\n\nNow all we have to do is plug in the relevant values, and we shall get the number of neutrons in an atom of silicon:\nA = 28.085\nn2 = 14\nP = \nN = \n\nSo, n1 = (A - (n2 * P))/N = \n\nSimple! Or at least, simpler! :)\n\nI know what you're going through...getting back into the swing of things after you've been away from school for a long time can be a pain. But keep on plugging away, it's worth it in the end! Good luck!
38228
By ohms law\nV = IR\n  = 3 amp * 3 ohms\n  = 9 amps/ohm\n  = 9 volt(since amp/ohm is given a special name volt)\nThe volt, symbol V, is named after the Italian scientist Alessandro Volta, who invented the voltaic cell and the electric capacitor.
430786
The formula for the capacity or volume, V, of a cylinder is:\n\nV = Π(d^2)h/4\nwhere:\nΠ = 3.1416 (value up to 4 decimal places)\nd = diameter of the cylinder\nh = height of the cylinder\n\nSo, merely substitute the values that you have and you will get the capacity or volume of the cylinder. Just make sure to use similar unit of measures both for the diameter and the height.
416798
105W\n\nA transformer changes the voltage, but inversely alters the current to the same degree. Therefore, using P=VI, the power is always the same.
892848
One of the most frequently used is E=IR    ;E =voltage    I=current   R= resistance. U can change this every way depending on the unknown.\n    Good luck
487088
#1) 32(.16)=.127v_2 ==> v_2=40.3\n#2)i'm too lazy\n#3).105(350=.345*v_2 ==> v_2=10.6\n#4)0+F(.10)=.40(19)  =>>F=76N
711363
The volume will be 549.5 mL.  Let me know if you want to see the work.   Use this equation PV/T=P*V*/T*.    P,V, and T are just the pressure, volume, and temperature for the initial system (they are usually represented as P1,V1, and T1 but I left out the numbers which should be subscripts for simpliofication because yahoo does not have many text options.)  P*,V*, AND T* are the pressure, volume, and temperature after the system has been changed.  You could use any units pretty much for the pressure and volume as long as you keep the units consistent.  However always use Kelvin for the temperature.  Kelvin = 273 + Celcius Temp.
245581
Energy of a capacitor = (CV^2)/2\nC = capacitance in farads\nV = voltage in volts\nenergy in joules of course
950045
Correct formula should be as follows:\n\nE = 1/2*I*w^2
802656
I suppose w = watt and c is coulomb \nI'm calculating with SI-Unit\n[W]/[C] = [V*A*]/[C] = [V*(C/s)]/[C] = [V/s] \nV= volt, A= ampere, s= time.\nthat is the best I can do for you, but I think you have been writing somthing wrong in your question.
100752
There are two relavent formulas,\nOhms Law: V = R*I\nwhere V is the voltage, R is the resistance, and I is the current.  Also,\nPower = V*I\n\nIf we know that power is 150 watts, then,\n150 = V * I,\nbut what is the current (I)?\n\nWe know the resistance is 95 ohms,\nV = 95*I --> I = V / 95\nSo plugging back into the power equation,\nP = V^2 / R \n150 = V^2 / 95 --> V = sqrt(150 * 95)\nso V = 119.4 volts --> 120 volts
1100598
voltage = current x resistance\nE = I x R  It IS Ohm's law. An easy way to remember the formula and it's configurations is to draw a circle and divide it in half horizontally. Above the line write "E". In the lower half divide the semicircle vertically and write "I" on the left, "R" on the right. It should look something like this:\n                                                     E\n                                                   I    R\nNow just cover up the one you need. and either divide, or multiply.