Volts Definition and 105 Threads

I'm trying to charge my cellphone and would like to know how many volts would cause the cellphone battery damage? Also, how many amps would an average phone need to be charged?

I just got a new external hard drive that wants 12 volts at 1.5 amps. it comes with a wall wart, but I'd rather find some other method to power it to keep it more portable friendly. (only need 1 outlet to power the drive and laptop) I've got several options, but i don't think most of these work...

Homework Statement (10.) It requires roughly 10 eV to ionize one hydrogen atom. How much energy (in joules) are needed to ionize all the hydrogen atoms in one mole of molecular hydrogen (H2)? [Recall: 1 eV = 1.6 × 10−19 J and Avogadro’s constant is about 6 × 1023.] Homework Equations...

what's special about a 0.1 to 0.2 volts current? thanks

I apologize for my very basic question, but I cannot find a straight forward answer anywhere. I want to know "Physically, what are volts". I understand that amps are a count of electrons passing a point in one second. I know the formula for Ohm's law, but that still doesn't answer the question...

I'm feeding the current in pulses via 50v 6800 mfd capacitor. Will it destroy the ignition coil instantly, or will just overheat it? It won't be for automotive use but for general high voltage experiments. As long as instant destruction is a remote possibility, it's easy enough to mitigate...

Hi, Im trying to understand the relationship between heat released in an energetically favourable chemical reaction and the released charged particles when the reactants are connected in a battery set up. If you mix Zinc and copper sulphate you get heat and the product. Connect the copper...

I have a question about the power usage of a light with a ballast. If the light is rated as a 1000w light and must be run through a ballast. I believe the ballast is like a transformer, because I saw somewhere that the bulb runs at 300 volts. So since Watts = amps x volts, does the wattage...

Hi guys and gals, please forgive the lame-o title, first poster here! I recently picked up a pretty fierce interest in electronics and I've been doing plenty of reading and experimentation but I have a few questions that I'm hoping will land on generous ears. What follows is a "brain dump"...

What is the limit of volts possible per amp? For whatever conductor, a superconductor let's say.

Thanks to all who will humor me with a serious answer. Solving my problem won't save the world but it will be fun. I am using a 3/4 hp garbage disposal to operate a mobile blender. The unit specs at 8.1 amps and is an induction motor. I have to use this unit because the lesser units do not...

Homework Statement The voltage(V) volts in a circuit at time(t) is given by V(t)=18(1 - e -4t/9) Find the expression for dV/dt. Hence evaluate dV/dt at (a)t=0 and (b)t=5 seconds Homework Equations Just wondering if this is right and if not where did i go wrong...

Is 5000 volts at 1mA safe if accidentally touched, if so, up to how many mA is safe at this voltage?

Hi all, I have almost completed a project that I power on the breadboard from USB and it works with TTL levels. But the situation is that I must make it powered by 12V and working with CMOS logical levels (because of the external input to the device). All my chips are CMOS already (HC to...

Ok i have a question about the difference between 240 volts and 120 volts. So from my knowledge power will come from a generator somewhere down the road. it will then make it to my house and a transformer will take it to 120/240. i get 240 120 from each line that are out of phase from each...

In my teacher gave us homework on electricity. One of the questions ask "what is the potential energy of the pair of charges? Answer in the units of V." Is that an error, or is there a way to convert Joules to Volts?

KW, Volts, Amp always confuse me. I have a project of 10kw generator, how do you measure that it is 10kw at first instance. for example if the output is 1200 volts, can it become 10kw or be a 10kw generator etc. What is the power requirement standard of a home ? how to fit the 1200 volt...

Homework Statement I always have problems when changing units form Joule form to Megaelectron Volts and vice versa...whats the easiest way to find them? Homework Equations The Attempt at a Solution I always get confused at the conversion part.

Homework Statement The fastest, most powerful Class III battery charger available is supposed to recharge 8.8 kWh into a Chevy Volt battery pack in 15 minutes. What is the most likely combination of DC volts and amps to do this and why? Homework Equations W=VxI (I = amps) a 120 V unit...

Hi, I have been viewing some publications related to space weather and have noticed that in many graphs and in the articles, the units AMeV appear very often. I am wondering what the A is for? My best guess is that means atomic, ie relating energies of ions rather than single electrons...

Homework Statement Hi, i have to calculate a calibration factor to change a measurement for velocity in volts from a vibration test rig into a measurement of velocity in m/s. Homework Equations I have data for velocity in volts and i am using the equation v=x'=awcos(wt) to...

Homework Statement How do I calculate Volts per cm (V/cm) with the following given? Two coaxial tubes with 20kV placed across them. Inner tube (actutally solid rod) has an OD of .5" and a length of 4" Outer tube has an OD of 1.00" and a length of 4" Homework Equations The...

I need a book for EE because the only thing I know is the word "volts" Hey guys I'm just started my freshman year in college and I chose EE as my major because its cool. But I realized that not only do I don't know a thing, but it seems that everyone in classes knows the material and knows...

Homework Statement A circuit has a 50 V battery, and 3 resistors. they are all 25 Watts, 1 is in series, 2 are parallel. Find the current of the circuit. Homework Equations V=IR P=IV The Attempt at a Solution I know how to do these fine when I'm given the resistances or the...

Question I was wondering how the concept of work can have units of volts? I mean work has the units of N/m = J =/ J/(A*S) = Volts? Yet I am reading they are equal? Can someone enlighten me?

Hello all, I was wondering if it is possible to increase voltage if you combine 2 DC motors together? I know that it is NOT possible to increase the voltage if you put it into a series circuit since it won't work. As for the batteries you can increase the volts if you put them into the...

i am planning to make a magnetic generator & i have a question : if i provide a disk with 12 numbers of neodymium (1x1”x1”cylinder) (n48) magnets around it , moving by motor clock wise at 1500 rpm , ( magnet specification: Br: 13.80- 14.20 KG, Hcb: > = 10.5 Koe, Hcj: > = 11 KOe ) the...

Homework Statement "Using the conversion factor from eV (electron volts) to Joules, determine which energy line for an electron dropping from one energy level to another in the energy diagram for hydrogen above would show a line at 435 nm in an emission spectrum." Homework Equations...

I'm wanting to build a dc power source of 1 million volts more would be nice but ill start with a million and work my way up from there. Any suggestions would be helpufull. Is it possible to build a 1 million volt capacitor or should i build a capacitor bank to smooth out the ac current after...

We use a 10v a.c. signal through to a small steel sensor (SMO 254) in wastewater - and the control device looks for a conductive path to ground to determine that the level of liquid is over the sensor. We don't use d.c. because of the electrolysis effect - but the circuit we use could have a...

Homework Statement A typical American family uses 800 kWh of electricity a month. What is the average current in the 120 V power line to the house? Homework Equations P=IV The Attempt at a Solution 800kW=800000W 800000=120I I=\frac{800000}{120} I'm getting this answer as...

In semiconductors it is known that the wider the band-gap the higher the output voltage, what is the theory behind this?

Hi everyone, What I am wondering is if there is a way to convert 5 volts to 12 volts. The application I will be using this for is a USB driven motor. The USB cable can only handle 5 volts and the motor is 12 volts. So I am wondering if there is a device or something simple to build that can...

The Q factor, also known as, Quality factor, Energy factor, Magnification factor, Merit factor, is the impedance of a coil divided by the resistance of the coil. I understand that in a series resonant circuit the voltage across the individual components at resonant frequency is the...

A parallel-plate capacitor with only air between the plates is charged by connecting it to a battery. The capacitor is then disconnected from the battery, without any of the charge leaving the plates. A.) A voltmeter reads 50.0 V when placed across the capacitor. When a dielectric is...

Homework Statement An ion is accelerated through potential diff. of 250 V, directly perpendicular to mag. field. Find radius of the path of the ion in the field. Given: mass (m)=2.5 x 10^-26 charge(q)= 1.6 x 10^-19 Volts= 250 V Mag. Field (B) = 0.50 T Homework Equations...

Im just curious what the units are for coulombs and volts in m kg and s.

Homework Statement Point A is at a potential of +240 V, and point B is at a potential of -120 V. An -particle is a helium nucleus that contains two protons and two neutrons; the neutrons are electrically neutral. An -particle starts from rest at A and accelerates toward B. When the...

I have a two wire outside light connection that the tester shows has 122 volts. It lights the neon circuit tester also. When I connect a regular 15 or 40 volt light it will not light up. Obviously I tested to see that these work fine on a different circuit. I added a two pin plug to the circuit...

The thing that is equal to electromotive force and potential difference is voltage.. right? And that is represented by a capital V? And the thing that is joules/coloumbs.. That is a unit called volts? represented by.. a lower case v? Or are they both essentially the same.. I'm confused...

Hi If anyone know's something about electromagnets. I was wondering if you could either explane to me, or show me where I could find some information about whether or not icreasing the amount of volt's would have an effect on how strong the electromagnet would be. That would be great!

Suppose the current drain (on average) of a LED is 2mA at 4.5v. Now suppose that 250 mAH 1.5v cells are being used to power this thing. I want to keep this LED powered for 504 hours (3 weeks), how many cells are needed and how should they be arranged? Now, here is my stab at the problem...

Hi, I have been given an assignment question detailing a circuit with a few resistors in as well as a capacitator. Further more the information given was the resitance of the resitors and that the battery had had a potential difference of 9 volts. The question's part a was workign out...

Anyone know of a place that sells 10 farad capacitors rated at 20k volts

Help me to wrap my brain around this notion of 'Electron Volts' The lamp on the table has 120 Volts... explain this MeV...in comparison to the Lamp Bulb please. Is every type of energy measured in the form of electricity in the world of Physics? if i get this info i can move deeper...

OK, Bear with me, I'm a mature student returning to the sciences after a 16 year break... I'm currently reading up on electricity and cannot, for the life of me, get my head around what 'appears' to be an inconsistency. Obviously my brain isn't 'seeing' the answer properly just yet so I...

How many standard homes using 3,600 kwh of electricty annually could be powered with a constant supply of 10,000,000 volts ?

If I have Volts, and I need eV, how do I get that? Is eV (energy format) = V (voltage format), so that if I have a value given in volts, I know that it would be the same in eV units? I know this is a dumb question, sorry guys...:blushing:

i need to create a source of several hundred thousand volts DC or greater, what would be the best approach to do this in DC?

Hello! I was reading Asimov on Physics the other day, and found that a watt is a measure of gm cm^2/s^3. That got me thinking, if voltage times current equals watts, what would voltage and current be a measure of? I have been trying to figure it out for a while, and came up with: current=...