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Electromagnetic Induction In the previous entry, we have seen that current, I can produce magnetic field, B. In this entry, we are going to look the other way round where B can also produces I. This concept that we will discuss here is induction. In 1831, Michael Faraday discovered that Power stations generate electricity by using electromagnetic induction. Diagram 1 Diagram 1 will helps us to explain the meaning of electromagnetic induction.The wire is connected to a galvanometer. Do you still remember the function of galvanometer? Please have a think!! What happens if we move the wire up and down in the region of the magnetic field? The galvanometer needle will flick to one side and another. It shows here that current is induced. But, if the wire does not moved, there will be no induced current. If there is an induced current, meaning there is also an induced voltage (or known as induced emf). Hence, we can conclude here that when a wire(conductor) is moving in a m

Electromagnetism The word electromagnetism is actually combining the words electric current , I (electro) and magnetic field, B (magnetism). Electromagnetism means magnetic field can be produced by the current. In matriculation syllabus, there are 3 cases of wire that carries current producing magnetic field . These wires are having different forms that are : 1) straight 2) Coil/loop 3) Solenoid. Equations: The equations show that they  are not the same. For the moment I'm not going to derive the equations of the magnetic field, but I'll just talk a little bit about it in order to give you some useful tips.                                                                         I believe many of you might get confused   (tertukar) at first with the equations of magnetic field due to the coil and that of straight wire . The important tip here is to look at the form of magnetic field line produced. The current-carrying wire produces circular form of

Magnetic Field, B To define Magnetic field, we start with the word field. Field means a region or space. The magnetic field is defined as a region where the magnetic force can be felt. In other words, a force (repel/attract) can be felt in the region. Bar Magnet We will find that 2 North(N) poles will repel if we bring the poles of two bar magnets together. Same goes to that of 2 South(S) poles. However North and South pole attracts. The strength and direction of the field are represented by lines. Knowing that, the direction of magnetic field is from North to South. Magnetic field is able to be detected by 1) Compass (have been used over 2000 years 2) Hall Probe Applications: Swipe cards, Video tapes & Computer discs -use magnetism to store information. History: In 1819, Hans Christian Oersted noticed that a compass needle was deflected by an electric current in a nearby wire. Remember!! the compass is used to detect any existance of magnetic field. By th

Potentiometer Potentiometer is a device that is equivalent to a circuit . It actually applies the same concept as that of potential divider. Do you still remember the principle of potential divider? If not, please refer here . Physically, this is how a potentiometer looks like ( one example): Normally we use the variable resistor as the potentiometer to control the voltage. Before I explain any further, please refer Diagram 1 and Diagram 2 below: Diagram 1: Potential Divider                                   Diagram 2: Potentiometer If we could realize, both Diagram 1 & Diagram 2 are quite similar. In Diagram 2, we have that black thick wire of from A to B. As we know, the resistance of any wire is always directly proportional to wire which means that , the longer the wire the higher the resistance.  l directly proportional with R In the middle of wire AB, we have S. S is where we can control in order to get our desired resistance. The chosen

Potential Divider Potential divider is also known as voltage divider. Its purpose is to be used to obtain any desired( wanted/preferred) smaller portion of voltage from a single source, V T. i.e. sometimes we want to use only part of the voltage provided by a battery and in order to get this, we use a potential divider circuit. Potential divider consists of 2 resistors that are connected to a voltage source. Diagram 1: Potential Divider  The basic principle of a potential divider circuit is that the resistors in the circuit act as the divider . The value of the resistance of each resistor  will influence the value of the voltage. Example/Application in real life: Th e rotary type of potentiometer. (1) We control the volume of the radio by twisting its knob. (2) We control the fan speed by twisting the 1-2-3-4-5 knob. Is not it?? So, what we are doing (example 1 & 2) here is we actually controlling the resistance, resulting in the voltage portion. T

Electromotive Force (emf) What is emf? It is defined as the energy provided by the source (battery/cell) to each unit charge that flows in a circuit. It means that, if we connect a battery in circuit, the battery will give energy to the charge, enable it to flow. emf = Energy (U)/ charge (q) We can see here that emf has the same unit as that of potential difference that is VOLT. So, please bear in our mind, electromotive force ( emf) is not actually a force, it is a potential difference of unit of VOLT. Internal Resistance (r) Consider this ⇩ case to comprehend more: We start with Diagram 2, Diagram 2 A battery of 1.5 V is connected to a circuit which consist of on external resistor, R. At the same time, we connect a voltmeter and the voltmeter reading shows the reading of 1.3 V !!! That is less than the emf value. The concept here is that the battery gives 1.5 joules of electrical energy to each coulomb (charge) that passes through it. But the energy that

Electricity We use electricity to transfer energy from one place to another. The energy is carried by electric current which flow through cable ( APP: from power station to homes) In a simple circuit ( Diagram: battery, bulb ), the battery transfer energy to the charge e , and keeps it circulating round the circuit. The bulb transfer energy to the surroundings as heat and light . Electric Current Electric current is a flow of electric charges. The lamp lights because charged particles are moving through it. Q:Why the ammeter is connected in series with other circuit element? Current is measured by ammeter. Ammeter is placed in the circuit so that  electrons pass through it. Electric current is defined as the rate on charge flow (Q/t). Meaning, the  more electrons (Q)  that pass the ammeter in  one second(t),  the higher the current. [Without battery in the circuit]  - A copper wire consists of copper atoms and free electrons. All metals have a structure like th

Salam'alaik & Hi, Many got confused with these two terms. Sound similar but actually not. Capacitor is a device. i.e. circuit device, while the capacitance is a measurement. Capacitance means the ratio of charge to the potential difference. Capacitance tells us the ability of a capacitor to store charges. I we have a capacitor with big capacitance, it means that it can store many charges.