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Circular Motion Figure 1: Ferris Wheel Circular motion is a motion of  any object that moves in a circle, or making a circular path . Simple examples of this motion are: 1)The earth orbiting the Sun; the earth acts as the object 2) The person in a Ferris Wheel; the person acts as the object 3) Hammer throwing; the metal ball acts as the object Before this we have learned linear motion and projectile motion from   Chapter 2. So now, for your information, we are going to learn one more type of motion in Chapter 6 that is circular motion . This motion is of course not the same as the linear motion. If you could recall, linear motion is the motion in a straight line. If  in linear motion , we have the term displacement , velocity and acceleration , so do the circular motion :) The names are also a bit different as you can see from the table below: LINEAR MOTION CIRCULAR MOTION Displacemenet , s Angular Displacement, θ ...

Momentum In order to understand what is 'momentum', we might look at these 2 examples. 1. A charging elephant ( high mass, low speed) 2. A speeding bullet ( low mass, high speed) The difference between these two is written in the bracket. Two quantities that are considered to look at are MASS and SPEED (velocity). Now, let us think, which one is harder to stop? What is your answer?? Ok , the answer is BOTH. Is not it? You may think twice if you're still confused. Knowing that, the measure of HOW HARD TO STOP A MOVING OBJECT is called MOMENTUM. Momentum is the product between mass and velocity. The common symbol used for momentum is p. ----->   p=mv Conservation of Linear Momentum A 'system' must has at least two moving objects moving in opposite directions. Remember that momentum is a vector quantity ( has direction). If the changes of momentum of the two objects are equal, they will cancel out as the directions are opposite. Hence, the over...

In the previous entry , we said that light is a WAVE based on its characteristics of showing wave phenomena. Knowing that, light is also a PARTICLE. Later in this writing, we will figure out how light can be also concluded as a particle. Photoelectric Effect Photoelectric Effect is the emission of electrons (called photoelectrons) from a metal surface when an incident light strikes the surface with enough energy/frequency. The photoelectric effect is represented by the Einstein's Photoelectric Effect equation: This equations consists of 3 terms which represent 3 items in the figure above that are , E is for the incident light , Wo is for the Metal and Kmax is for the Photoelectrons. The incident light energy must be bigger than the work function of the metal . Work function is basically the energy possessed by the electrons in the metal. Hence, to free these electrons from the metal , the incident light must have enough energy to displace the electrons. The incid...

Light Phenomena Knowing that, Light can only be 'said' as light if it is able to undergoes a few phenomena and these are i) Reflection ii) Refraction iii) Diffraction iv) Intereference Light is actually a wave. That is why it could do what a wave does. In Malaysia Matriculation syllabus, Reflection and refraction are discussed separately from diffraction and interference. The first two are in Geometrical Optics chapter while the other two are in chapter Physical Optics. Geometrical optics deals more with ray diagram, few parameters like focal length, radius and so on, and that is how it relates with the word 'geometric'. Thank you, Mdm Ummi Atiah KMPk ~  May it Benefits You ➽💕

Root Mean Square Current As mentioned in the previous post , the value of AC is always changing. Then, how do we measure its value??? We could not use the maximum value of the current Io, because it only occurs at a moment. The average current is ZERO . Hence, one effective value that we could use the root mean square value. Irms . The formula for   Irms is given by: where Io is maximum current. Irms is the value that is equivalent to a steady direct current .  We can investigate this by comparing 2 circuits containing lamp each. circuit 1 uses battery as the source, while circuit 2 uses a.c. supply. AC supply is adjusted so that both lamps are equally bright. At this point, DC and AC supplies are transferring energy to the lamps at the same rate (Power).  By equating the Power of both circuits, we can deduce the equation of  Irms as above. Therefore, the d.c. voltage equals the r.m.s. value of the a.c. voltage.  From the the graph below and th...

Alternating Current (AC) DC versus AC  Remember in Chapter 18, we learned direct current  (DC). Direct current means a current that is flowing in only one direction, that is from positive terminal to the negative terminal of the battery in the circuit. Battery is one of the examples of DC source, while AC generator is the source of AC. The meaning of the word 'alternate' is something occurs by turns; first one and then the other. Knowing that alternating current (AC) means the direction of a current always changing its turns. The proper definition of AC  is a current that repeatedly reverses its direction . Alternating current is not only changing its direction, but it also changes its value. It does not have any similar values. This can be seen clearly from the GRAPH 2 below, in which you can also compare it with that of DC. GRAPH: AC VERSUS DC When it comes to calculation, we don't have any problem in writing down the value of DC because it is alway...

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...