Physical Science Reviewer PDF - Benigno N. Aquino High School - SY 2024-2025

BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Reflection Properties of Light Using Plane Mirrors...

BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Reflection Properties of Light Using Plane Mirrors reflected in one direction too, forming a clear image. The ray hitting the mirror is The bouncing of light rays is called reflection. There are two types of called an incident ray while the one that bounces off the surface is known as a reflection, the specular reflection that occurs on materials with smooth reflected ray. An imaginary line perpendicular to the surface where the light rays surfaces like mirror and calm water, and diffused reflection which on strike is called normal line. The space between incident ray and the normal line is the the other hand occurs on materials with rough surfaces such as the angle of incidence while the angle between the normal line and the reflected ray is wall or your book. the angle of reflection. It obeys the Law of reflection which states that the angle of incidence is always equal to the angle of reflection. If this is true to all opaque surfaces, why can’t a wall or a book produces an image like the way mirrors do? This is because on a rough surface, each light ray that strikes it has different orientation making the rays reflected in different directions too (see figure 13B). Whereas in a mirror, the light rays are traveling in one direction thus 1  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Two types of mirrors. Plane and Spherical/ Curve Mirrors mirror. It has the same characteristics of a plane mirror. This is just a There is significant difference in the way you look in these different types of transparent glass and acts as a mirror because of the significant mirrors. The images formed may be different in terms of type, position, size, difference in the brightness on each side. The people on the brighter orientation, and location. There are two types of images, the real and the side could see themselves because of too many rays bouncing off virtual. When the image is formed inside the mirror, it is called a virtual image while the people in the darker area could see through as if it is a while the images formed on the surface of the mirror or an image that can be transparent window. The viewing area is darker than the area to be observed. projected on screen is a real image. In terms of image position, there are two types - upright (or erect) and inverted (if your image becomes upside down). Reflection Properties of Light The size of the object can also be altered when looking at certain types of Using Spherical Mirrors mirrors. There are two types of curved mirrors, the concave and convex mirror. Situational Examples A concave mirror is curved inward while the convex is curved Have you tried raising your right hand in a mirror? If you have done outward. Due to the difference in curvature, the light that hits them this, you probably noticed that the image raised the left hand. This is is reflected differently (See Figure1). called lateral reversal. Now try to stand a meter away from the mirror, then slowly move closer to the mirror until your body touches it. Your image does the same, right? In a flat or a plane mirror, your distance from the mirror is just equal to the distance of your image from the mirror. You are very familiar with plane mirror because this is the type of mirror that we are commonly using at home. Have you passed an establishment with glass wall, and you see yourself as if it is a plane mirror? You started checking your make-up or your outfit but the people behind it can’t stop smiling on what you are doing. You can’t see them, but they can see you. This is two-way 2  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter In a concave mirror, the light rays are reflected inward making the reflected rays converge or meet at a common point which is why this is also called a converging mirror. The point where all the reflected rays meet is called the focal point or focus. Its converging property makes it important in a flashlight. It focuses the reflected rays to intensify the light. On the other hand, the light rays are reflected outward in the second type called convex. Since the reflected rays diverge, this mirror is then called a diverging mirror. Its diverging property makes it useful in the car’s side mirror because it gives the driver a wider field of view. To understand better the properties of a concave Mirror and convex mirror, it would be best for you to be familiar with the terms associated with them. (You may use Figure 2 to visualize the parts). If a curved mirror is thought to be part of a sphere, it has the geometric center called the center of curvature (C). This is the center of the sphere. The mirror itself has its physical center called vertex (V). The mid-way between the vertex and the center of curvature is called the focus or focal point (F). The distance between the vertex and the center of curvature is the radius of curvature (R) while the distance between the vertex and the focal point is the focal length (f). This focal length is always half the radius of curvature. The imaginary line passing through the center of curvature, focal point, and the vertex is termed as the principal axis (P). 3  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter When the image is found on the screen or on the same side as the object, it is called real while those located behind or inside the mirror are termed virtual images. In terms of the size of the image, you can describe it as the same size, reduced or enlarged. For the position, there are two types-the inverted and upright. If it follows the position of the object, the image is described as upright while if the image is upside-down, then it is inverted. You can describe the location of the image with reference to the center of curvature, focal point, and vertex of the mirror. Concave mirrors form images that are of different characteristics. This depends on the location of the object with respect to the mirror. The distance of the object is represented by do while the distance of the image from the mirror is denoted by di. Rules in Ray Tracing: Rule 1: A ray parallel to the principal axis, passes through the focal point after reflected by the mirror. Rule 2: A ray that passes through the focal point will be IMAGE DESCRIPTION: reflected by the mirror parallel to the principal axis. Rule 3: Any ray that passes through the center of curvature(C) Size: Reduced will be reflected to its incident path. Position: Inverted Rule 4: If the light ray strikes the vertex of the mirror, it will Type: Real bounce on the other side of the plane at an equal angle. Location: Between C & F 4  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Mirror Equation and Magnification – use LAS 7 as your reference. Electric Motor vs Electric Generator. Motor and Generator have common parts. This means the device In 1820, Hans Christian Oersted, a Danish Physicist, discovered can act as a motor or as a generator depending on what is in the that magnetism was produced by current-carrying wires. It input form, may either be electrical energy or mechanical energy. means electric current produces magnetic field. Generally, motor converts electrical energy into mechanical In 1831, Michael Faraday of England and Joseph Henry of United energy while generator converts mechanical energy into States found out that moving a wire in a close circuit across a electrical energy. magnetic field will make electric current flow in the circuit. It Motor and Generator have similarities. Both have essential parts means magnetism produces current. like magnet coils and spinning part. They work on the principle The two words, Electricity and Magnetism, are very much related of rotation and convert energies. They are based on the principle to each other. There are two electromagnetic devices: the of a magnetic field and electric field and uses concept of electric electric motor and electric generator. current at any point. They are electromagnetic devices. These devices have similarities and differences. Electric Motor is a device which converts electrical energy into Here are the essential parts and functions of electric mechanical energy. motor and electric generator. Electric current is Armature- coil of wire that turns in the magnetic field needed by these appliances to work! Brushes- copper metal chips that conduct electricity from The motor of the fan converts electric energy into mechanical the source to the Commutator energy. Commutator- a split ring that reverses the current every The reverse conversion is a device that converts mechanical half turn energy into electrical energy. Generators generate electricity. Field Magnets- bar magnets that produces magnetic field 5  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Differences between the electric motor and electric generator. 6  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter The Working Principle of Simple Electric Motor. C. Commutators are devices which revert the polarity of the static An electric motor is an electrical machine that converts electrical magnets, this is done so the magnetic field which crosses over the energy into mechanical energy. Most electric motors operate through rotor will always induce a continuous rotation. Even though they the interaction between the motor's magnetic field and electric current were very useful in the past, commutators are not seen very often in a wire winding to generate force in the form of torque applied on the today since they have been displaced by semiconductor switches. In motor's shaft. In more understandable terms, an electric motor takes case a motor has a commutator it's called "brushed", and if it doesn't voltage and current and transforms it into force and velocity. have a commutator it's called "brushless". It is to be noted that Electric motors are very useful, especially for their simplicity and size commutators are only encountered in DC motors. They are of the sort of plug-and-play devices, in comparison to other types of motors like internal combustion engines. Electric motors have D. The rotating magnets are magnets which are attached to the rotor. also evolved over time. In the past we used to have brushed DC Usually, these magnets were made with wounded coils which are fed motors but now we mostly use brushless DC motors and AC motors. with DC current. However, with the implementation of AC current, This is important since the key parts of electric motors have also these magnets were substituted by aluminum bars inside a cage in changed over time. The main parts of any electric motor are: the rotor, this was done since a magnetic field is induced on those aluminum bars. In this case the motor is called "Induction motor". A. The stator corresponds to all non-moving parts of the machine. This includes the non-rotating magnets, the windings, the outer shell, and the commutator. B. The rotor corresponds to all moving parts of the machine. This includes the rotating magnets (or aluminum bars), the shaft, and any object which moves when the motor is working. 7  BENIGNO NINOY S AQUINO HIGH SCHOOL SY 2024- 2025 Second Quarter Prepared by: Mr. Raniel Enguancho Biala. MA, LPT Science Teacher November 7, 2024 8