# 22 current and resistance relationship

Dr. Mangala Singh, 1P22/92 Brock University. Current. Q. I t. ∆. = ∆. If electric charge (e.g. electron) Step 2: Identify relationship between these quantities. Current is a measure of the rate of flow of electric charge through a circuit. A resistor is a component designed to reduce the current. ○ A variable . Page 22 . DC Circuit Theory. The fundamental relationship between voltage, current and resistance in an electrical or electronic circuit is called Ohm’s Law. Then all basic electrical or electronic circuits consist of three separate but very much related electrical quantities called.

One cannot see with the eye the flowing of energy through a wire. However, a reaction within the air to the energy passing through it. So, as to notice this energy transfer, we should use measurement tools like a spectrum analyzer, multimeter and oscilloscope. This oscilloscope is used to visualize what is happening with the charge in a system. All materials are made up from atoms, each atom consist of protons, neutrons and electrons.

These three are together in the atom. But, if we separate them from each other they want to reform to exert a potential of attraction called a potential difference.

When we build a closed circuit, these electrons move and drift back to the protons because of their attraction to create a flow of electrons, this is called electric current.

The electrons do not flow freely due to the restriction of flow of electrons, this is called as resistance. Then all basic circuits comprise of three separate quantities, namely voltage, current and resistance. Electrical Charge Electricity is the movement of electrons, it creates charge which we can connect to do the work, your light, phone, stereo, etc. These all are operated using the basic power source that is, the movement of electrons. Current is the flow of electrons Resistance is defined as, it is the tendency of a material to restrict the flow of current.

So, when we discuss about these values, the behavior of electrons in a closed loop circuit allows charge to move from one place to another. He described a unit of resistance which is defined by voltage and current.

The difference between voltage and current and resistance is discussed below. In this equation, voltage is equal to the current and that is multiplied by resistance. Basic Circuit Diagram of V, I and R In the above circuit, when the voltage and resistance values are given, then we can calculate the amount of current. The differences between V, I and R are discussed below. The voltage is defined as, it is the potential difference in charge between the two points on a circuit, it is also called electromotive force.

One point has more charge than another. The unit volt is termed after invented by Italian physicist Alessandro Volta. The same applies for flowing currents: The resistance R of a material depends on its length, cross-sectional area, and the resistivity the Greek letter rhoa number that depends on the material: The resistivity and conductivity are inversely related. Good conductors have low resistivity, while poor conductors insulators have resistivities that can be 20 orders of magnitude larger.

Resistance also depends on temperature, usually increasing as the temperature increases. For reasonably small changes in temperature, the change in resistivity, and therefore the change in resistance, is proportional to the temperature change. This is reflected in the equations: At low temperatures some materials, known as superconductors, have no resistance at all.

Resistance in wires produces a loss of energy usually in the form of heatso materials with no resistance produce no energy loss when currents pass through them. Ohm's Law In many materials, the voltage and resistance are connected by Ohm's Law: These materials are called non-ohmic.

## Relationship and Difference Between Voltage, Current and Resistance

We'll focus mainly on ohmic materials for now, those obeying Ohm's Law. Example A copper wire has a length of m and a diameter of 1. If the wire is connected to a 1. The V is the battery voltage, so if R can be determined then the current can be calculated.

The first step, then, is to find the resistance of the wire: L is the length, 1. The resistivity can be found from the table on page in the textbook. The area is the cross-sectional area of the wire.

Electric Current & Circuits Explained, Ohm's Law, Charge, Power, Physics Problems, Basic Electricity

This can be calculated using: The resistance of the wire is then: The current can now be found from Ohm's Law: It has units of Watts.

Batteries and power supplies supply power to a circuit, and this power is used up by motors as well as by anything that has resistance.

The power dissipated in a resistor goes into heating the resistor; this is know as Joule heating. In many cases, Joule heating is wasted energy. In some cases, however, Joule heating is exploited as a source of heat, such as in a toaster or an electric heater.

The electric company bills not for power but for energy, using units of kilowatt-hours. It does add up, though.

### Relationship and Difference Between Voltage, Current and Resistance

The following equation gives the total cost of operating something electrical: Try this at home - figure out the monthly cost of using a particular appliance you use every day. Possibilities include hair dryers, microwaves, TV's, etc. The power rating of an appliance like a TV is usually written on the back, and if it doesn't give the power it should give the current.

Anything you plug into a wall socket runs at V, so if you know that and the current you can figure out how much power it uses. The cost for power that comes from a wall socket is relatively cheap. On the other hand, the cost of battery power is much higher.

Although power is cheap, it is not limitless. Electricity use continues to increase, so it is important to use energy more efficiently to offset consumption. Appliances that use energy most efficiently sometimes cost more but in the long run, when the energy savings are accounted for, they can end up being the cheaper alternative. Direct current DC vs. If the circuit has capacitors, which store charge, the current may not be constant, but it will still flow in one direction.

The current that comes from a wall socket, on the other hand, is alternating current. With alternating current, the current continually changes direction. This is because the voltage emf is following a sine wave oscillation.