Physics can be a broad subject with many different topics that need to be understood. Students in Canada can start to enroll in a physics call in grade 11 or 12. Although physics is made available to students most are unaware of the fascinating things about physics. We have created a series of articles around physics that can help students make the right choice in deciding if physics is for them. This article focuses on waves. After reading this article continue learning about other physics topics. For a complete guide to physics in high school read our article High School Physics Syllabus.
Properties of Waves
Waves are one of the many ways energy can be transferred between stores. They can be described as oscillations or vibrations and it is important to note that all waves transfer energy but they do not and will not transfer matter.
Waves have many different parts and they can be described using the following terms:
- Rest position,
- Time period,
Diagrams are examined by pupils to further understand the location of the different parts of the waves.
Wave Period and Wave Speed
The time period a wave can be calculated using the following equation:
(Image is courtesy of bbc.com/bitesize/guides)
The period of time is measured in seconds and the frequency is measured in Hertz. After the time period of a wave has been determined by students the next move onto the equation of the wave speed which is the following:
wave speed = frequency x wavelength
After understanding frequency, students will then measure the speed of sound in the way and in the way. Scientists have learned that the air is made up of tiny particles. During sounds, these particles vibrate and collide with each other. Students will use the following equation to determine the speed of sound.
Transverse and Longitudinal Waves
Students will next learn about transverse and longitudinal waves. These waves are parallel to the direction they travel. Some examples of longitudinal waves include sound, ultrasound and seismic-P waves. These waves show areas of compression, regions of high pressure due to the particles being close together, and rarefaction, low pressure because particles are spread farther apart. An example of transverse waves is the water ripples you'll see on the surface or vibrations from a guitar string.
These are transverse waves and they transfer energy as radiation to an absorber and can travel through a vacuum at 300 million metres per second (m/s).
The electromagnetic spectrum shows in which ways waves have a variety of uses in different areas. Here are some of the most common uses per section of the spectrum:
- Radio waves: used for communication such as in television and radio,
- Microwaves: for household microwaves used for cooking and satellite communications,
- Infrared: the infrared light can be seen in electric heaters and in infrared cameras that can detect people in the dark,
- X-Rays: used by health-care professionals to detect broken bones in a patient.
Reflection and Refraction
All waves will either reflect or refract depending on the right circumstances. Humans can see images or colours based on the reflections and refraction of light.
The reflection waves of sound cause echoes and the reflected waves of light can be observed in different ways. Pay close attention to the following examples:
- Specular reflection: this reflection can be observed from a smooth and flat surface. This can be seen in a mirror and the image is upright and virtual,
- Diffuse reflection: if the surface is rough the reflected light will be scattered in all directions. This can often cause a distorted image that does not well reflect the original.
Refraction is the change in direction of a wave at the boundary between two clear materials. It can cause optical illusions and the density of a material affects the speed of the wave. For example, the light passing through a dense transparent material will travel slower than it would if the material was less dense.
Sound and Ultrasound - Higher
Sound has been proven to be caused by vibration particles. The sound waves can travel through solids, liquids and gases. For example, high-frequency sound waves are high pitched and low-frequency sound waves are low pitched. When it comes to amplitude, high amplitude sound waves are loud and low amplitude sound waves are quiet.
Ultrasounds waves can not be seen or hear but they serve many different purposes. The vibrations of the high-frequency ultrasound break up the kidney stones and the dirt that was damaging the jewellery.
These waves are produced by earthquakes in the Earth's crust and there are two different types, P-waves and S-waves. They are very different from each other and have very identifiable properties such as:
- P-waves: these are longitudinal waves, are faster and can travel through solids and liquids,
- S-waves: are transversal waves, slower than the aforementioned and can only travel through solids.
Lenses are precisely shaped pieces of glass that have been created for use in reading glasses, microscopes, telescopes etc. There are real and virtual images that can be formed on a lens. A real image is an image that can be projected onto a screen and a virtual image often appears to come from behind the lens. Lenses can also be divided into two sections, convex and concave.
The images on convex lenses depend on the lens used and the distance from the object to the lens. Cameras and human eyes contain convex lenses and the image seen can be inverted, diminished or real. Concave lenses always produce images that are upright, diminished or virtual. Peephole lenses are a good example of concave lenses. Students examining this section learn the primary differences between convex and concave lenses.
Lenses and curved images can produce magnified images. Magnification is the size of an image compared to the size of the object. Magnification can be calculated using a basic equation:
(Image is courtesy of bbc.com/bitesize/guides)
Since magnification is a ratio of two lengths, it has no units.
Absorption and Transmission of Light
Waves get absorbed by a surface, then the energy of the wave is transmitted to the particles on the surface. If the object is opaque the colours of light are absorbed. The absorption of the other colours in the spectrum of white light is the reason why certain objects have defining colours that can be identified by the human eye.
Discover various physics lessons on Superprof.
Black Body Radiation
Black bodies or objects are perfect absorbers and emitters of radiation. It is important to note that an object that is a good absorber is also a good emitter. The worse known absorbers and emitters are white and shiny objects since they reflect all visible light wavelengths.
The Earth's Temperature
Earth's temperature depends on a few things such as water vapour, methane and carbon dioxide. Students will have the chance to learn more about all these factors with more in-depth studying during their physics class.
Sample Exam Questions
Knowing what type of answers to expect on an examination greatly increases the confidence of students. The GCSE Physics subject assessments are divided into two sections: the first four topics on the first exam and the last four topics on the second exam.
The question types are the same and examples that could be on the test are offered on the internet to be studied with anticipation. Here are the question types:
- Multiple choice questions,
- One and two mark questions,
- Three and four mark questions,
- Maths questions,
- Practical questions,
- Six mark questions,
For more information and examples of each type of question that might be considered on the exam, the BBC Bitesize website offers invaluable help.
Physics can be the perfect topic to learn more about the world. Students that pursue physics can expect to work in an exciting career and be passionate about their work. It all starts when they enroll in a physics class. Students should check out other essential topics of the high school Physics subject is energy, electricity, particle model of matter, atomic structure, forces, magnetism and electromagnetism and space physics.