Malaysia SPM syllabus Form 5 Physics Chapter 7. Part 2: Electric Current and Potential Difference::Slide-making service available. For more. Ohm' Law Aim: To investigate the relationship between current and potential difference (ohm's law). Prediction: I predict that as the current increase or decrease. Current Electricity - Lesson 1 - Electric Potential Difference .. your understanding of the mathematical relationship between work, potential energy, charge and.
Current, voltage and resistance
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.GCSE Physics Revision: Calculating current and 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.
To investigate the relationship between current and potential difference (ohm’s law).
The unit volt is termed after invented by Italian physicist Alessandro Volta. The term volt is represented by the letter V in schematics. The measuring instrument of voltage is the voltmeter. By definition, the electric potential difference is the difference in electric potential V between the final and the initial location when work is done upon a charge to change its potential energy.
In equation form, the electric potential difference is The standard metric unit on electric potential difference is the volt, abbreviated V and named in honor of Alessandro Volta. One Volt is equivalent to one Joule per Coulomb.
If the electric potential difference between two locations is 1 volt, then one Coulomb of charge will gain 1 joule of potential energy when moved between those two locations.
If the electric potential difference between two locations is 3 volts, then one coulomb of charge will gain 3 joules of potential energy when moved between those two locations.
And finally, if the electric potential difference between two locations is 12 volts, then one coulomb of charge will gain 12 joules of potential energy when moved between those two locations.
Electric Potential Difference
Because electric potential difference is expressed in units of volts, it is sometimes referred to as the voltage. Electric Potential Difference and Simple Circuits Electric circuits, as we shall see, are all about the movement of charge between varying locations and the corresponding loss and gain of energy that accompanies this movement. In the previous part of Lesson 1, the concept of electric potential was applied to a simple battery-powered electric circuit.
In that discussionit was explained that work must be done on a positive test charge to move it through the cells from the negative terminal to the positive terminal. This work would increase the potential energy of the charge and thus increase its electric potential. As the positive test charge moves through the external circuit from the positive terminal to the negative terminal, it decreases its electric potential energy and thus is at low potential by the time it returns to the negative terminal.
If a 12 volt battery is used in the circuit, then every coulomb of charge is gaining 12 joules of potential energy as it moves through the battery. And similarly, every coulomb of charge loses 12 joules of electric potential energy as it passes through the external circuit. The loss of this electric potential energy in the external circuit results in a gain in light energy, thermal energy and other forms of non-electrical energy.
With a clear understanding of electric potential difference, the role of an electrochemical cell or collection of cells i. The cells simply supply the energy to do work upon the charge to move it from the negative terminal to the positive terminal.
By providing energy to the charge, the cell is capable of maintaining an electric potential difference across the two ends of the external circuit. Once the charge has reached the high potential terminal, it will naturally flow through the wires to the low potential terminal.
BBC Bitesize - GCSE Physics (Single Science) - Current, voltage and resistance - Revision 4
The movement of charge through an electric circuit is analogous to the movement of water at a water park or the movement of roller coaster cars at an amusement park. In each analogy, work must be done on the water or the roller coaster cars to move it from a location of low gravitational potential to a location of high gravitational potential.
Once the water or the roller coaster cars reach high gravitational potential, they naturally move downward back to the low potential location. For a water ride or a roller coaster ride, the task of lifting the water or coaster cars to high potential requires energy. The energy is supplied by a motor-driven water pump or a motor-driven chain.
In a battery-powered electric circuit, the cells serve the role of the charge pump to supply energy to the charge to lift it from the low potential position through the cell to the high potential position. It is often convenient to speak of an electric circuit such as the simple circuit discussed here as having two parts - an internal circuit and an external circuit. The internal circuit is the part of the circuit where energy is being supplied to the charge.
For the simple battery-powered circuit that we have been referring to, the portion of the circuit containing the electrochemical cells is the internal circuit. The external circuit is the part of the circuit where charge is moving outside the cells through the wires on its path from the high potential terminal to the low potential terminal.
The movement of charge through the internal circuit requires energy since it is an uphill movement in a direction that is against the electric field. The movement of charge through the external circuit is natural since it is a movement in the direction of the electric field.
When at the positive terminal of an electrochemical cell, a positive test charge is at a high electric pressure in the same manner that water at a water park is at a high water pressure after being pumped to the top of a water slide. Being under high electric pressure, a positive test charge spontaneously and naturally moves through the external circuit to the low pressure, low potential location.
As a positive test charge moves through the external circuit, it encounters a variety of types of circuit elements.