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Voltage of the battery and resistance in the wire or lightbulb.
Ohm's Law: E = I * R
E is electromotive force and is measured in volts
I is intensity and is measured in amps
R is resistance and is measured in ohms
Voltage is the pressure that pushes electrons from one atom to the next in the conductor. This flow of electrons (flow of electrons is current) is measured in amps. Resistance is the opposition to current flow. You need enough voltage (pressure) to push the electrons through the resistance to be able to have current flow. Ohm's Law can be rewritten as I = E / R to solve for how much current would flow in a circuit if you know how much voltage was applied to how much resistance.
ANSWERThe previous explanation is an excellent mid-20th century textbook answer to the question, but rather inadequate for what we know in the early-21st century.THE SHORT ANSWER IS THAT CURRENT IS CAUSED BY POWER (OR BY ENERGY, WHICH IS POWER WITH A TIME FACTOR). Now, on to the details.
What is actually flowing in a DC (direct current) electrical circuit is charge, a fundamental property of matter like mass and time. We still don't really understand what charge and mass and time are, but that doesn't prevent us from understanding how we can use them. Electrons are the easiest place to find charge, because almost everything is made of atoms and the outside of every atom is a cloud of electrons, each electron carrying one charge.
Some materials hang on to their electron clouds and the charges in the clouds very tightly; we call these materials insulators. In other materials, especially metals, the electron clouds are less tightly held; and electrons and their charges are free to leap from cloud to cloud. We call these materials conductors.
So direct current is actually a flow of charges. We measure current by measuring how much chargepasses a particular point in the circuit in one second of time. Notice how current is described using 2 of the most fundamental physical properties that we know of, chargeand time.
But charges cannot just take off and start flowing all by themselves. They need to have the property of energy in order to be able to move. Voltage or EMF is a concept that we use to describe how much energy is present for each charge. "Low voltage" means that there is very little energy for each charge; "high voltage" means that there is a great deal of energy for each charge.
This may make it sound like the charges are carrying the energy, but the relationship is more complicated than that. The electrons and charges trudge rather slowly around the circuit (a few mm or cm per hour), while the energy races from the power source to the far end of the circuit at fantastic speed (a million miles per hour or more). Obviously the energy is not directly attached to the electrons or the charges, but the slow motion of the electrons and charges makes the incredibly fast motion of the energy somehow possible.
Resistance is a property that removes energy from the circuit and moves it someplace else in a different form. It might move the energy in the form of heat in a toaster, it might move the energy in the form of light in a lightbulb, it might move the energy in the form of sound in a stereo or iPod, etc.
The main source of power or energy for our homes and businesses is in the form of AC (alternating current). In an AC circuit, the electrons and charges stay pretty much in one place and slowly wave back and forth. This sets up a power or energy wave called an electromagnetic wave, which is capable of carrying power or energy at a speed of roughly 35 million miles per hour. Because of the electromagnetic nature of AC current, we can use magnetic devices called transformers to raise or lower the voltage or EMF. This is not possible with DC current.
So the best way to move electrical energy long distances is to use AC, while most of our favorite electronic gadgets require DC. Fortunately, it is quite simple to change AC to DC; changing DC to AC is possible but comparitively complicated.
Finally, scientists have devised a system of units to describe specific amounts of the different properties we have been talking about.
The basic unit of power is called the watt.
The basic unit of energy is called the watt-second or joule.
The basic unit of charge is called the coulomb.
The basic unit of current is called the coulomb per second or ampere.
The basic unit of voltage or EMF is called the joule per coulomb or volt.
The basic unit of resistance is called the ohm.
What else can I help you with?
What happens to a wire when and electric current passes through it?
When an electric current passes through a wire, the wire heats up due to the resistance in the material. The current causes electrons to flow through the wire, creating a magnetic field around it. This effect is used in electromagnets and electric motors.
What happens when an electric current passes through a wire?
When an electric current passes through a wire, the flow of electrons creates a magnetic field around the wire. This phenomenon is known as electromagnetism. The strength of the magnetic field is directly proportional to the amount of current flowing through the wire.
How can you produce current in a wire with a magnet that is stationary?
When a magnet is stationary near a wire, it can produce current in the wire through electromagnetic induction. This happens when the magnetic field from the magnet interacts with the electrons in the wire, causing them to move and create an electric current.
What happens to the electric current in a wire as voltage is increased?
As voltage is increased, the electric current in a wire also increases because the relationship between voltage, current, and resistance is described by Ohm's Law (V = IR). If resistance remains constant, a higher voltage will result in a higher current flowing through the wire.
What happens to the charge of a wire when a current flows through it?
When a current flows through a wire, the charge within the wire does not change. The charge carriers (usually electrons) move along the wire, creating an electric current, but the total charge remains constant.
What happens to copper wire because of the moving magnet?
The copper wire carries an electric current.
What happens to a wire when and electric current passes through it?
When an electric current passes through a wire, the wire heats up due to the resistance in the material. The current causes electrons to flow through the wire, creating a magnetic field around it. This effect is used in electromagnets and electric motors.
When a wire is made smaller the resistance increases. what happens to electric current?
increase
What happens when an electric current passes through a wire?
When an electric current passes through a wire, the flow of electrons creates a magnetic field around the wire. This phenomenon is known as electromagnetism. The strength of the magnetic field is directly proportional to the amount of current flowing through the wire.
How can you produce current in a wire with a magnet that is stationary?
When a magnet is stationary near a wire, it can produce current in the wire through electromagnetic induction. This happens when the magnetic field from the magnet interacts with the electrons in the wire, causing them to move and create an electric current.
What happens to the electric current in a wire as voltage is increased?
As voltage is increased, the electric current in a wire also increases because the relationship between voltage, current, and resistance is described by Ohm's Law (V = IR). If resistance remains constant, a higher voltage will result in a higher current flowing through the wire.
What happens to the charge of a wire when a current flows through it?
When a current flows through a wire, the charge within the wire does not change. The charge carriers (usually electrons) move along the wire, creating an electric current, but the total charge remains constant.
What happens to the needle of a compass as a wire carrying electric current is placed across it?
The needle of a compass will deflect from its original position when a wire carrying an electric current is placed across it. This is due to the magnetic field created by the current in the wire, which interacts with the magnetic field of the compass needle, causing it to move.
What are 3 ways to induce an electric current in a wire?
You can induce an electric current in a wire by moving a magnet near the wire, passing a current through a nearby wire, or changing the magnetic field around the wire.
What happens when electric current is passed through Cu wire?
When electric current is passed through a copper (Cu) wire, the free electrons in the wire start to move in the direction of the current flow. This movement of electrons constitutes an electric current, which generates heat due to resistance in the wire. The wire may also produce a magnetic field around it as the electrons move.
What happens to the electric current when the wire is made smaller?
If wire delivering a certain amount of current is made narrower, the resistance of the wire will increase. This will limit current, and the wire will warm up some. If the wire is made shorter, resistance will decrease. The electrical codes have well published limits on the amount of current different types of wire can carry.
Why does a bare electricity wire with current flowing though it give an electric shock and what happens if the body wet?
Electric current flows on the outside of the wire, not inside the wire. An insulated wire covers that surface where the current is flowing so that you are not touching the wire which actually carries the charge. The body has a pretty large eletrical resistance. If wet, the salts from sweating, form a more conductive surface.
