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Chapter 17: Lesson 4 - Math
Chapter 17: Lesson 4 - Math
Equations:
Equations:
An important piece of paper to have handy when studying physics is your equation sheet. You never have to memorize any of the equations in class. You just have to know how to use them, manulipate them to solve for the unknown, and what each abbreviation stands for. A copy of the equation sheet is under resource materials on this website and on google classroom. It can also be found HERE. It is helpful to have a copy handy so you can mark equations on the sheet when we talk about them.
Reminder from Lesson 2: Radius of Curvature
Reminder from Lesson 2: Radius of Curvature
To find the radius of curvature, r, of a concave mirror, you use the equation, r=2ƒ. The focal length is half of the radius of curvature.
Mirror Equation
Mirror Equation
The mirror equation can be used to locate the image and find its size. The focal length is abbreviated with a ƒ. The distance from the mirror to the object is abbreviated with a do and the distance from the mirror to the image is abbreviated with a di.
When using this equation, you need to make sure that the units for ƒ, do, and di, are all the same. They can all be in cm, m, or km, but all parts need to have the same unit.
The focal length is positive for the concave mirror and negative for a convex mirror because the focal point is behind the mirror for a convex mirror.
We will be using this equation for chapter 18 when we learn about lenses.
Magnification Equation
Magnification Equation
Magnification is the ratio of the size of the image, hi, to the size of the object, ho. Magnification is abbreviated with a m. There is no unit for magnification since it is a ratio.
Magnification is related to the distances to the mirror by the equation shown here. The image position is positive for a real image when using the equation.
If the distance from the mirror to the image is negative, the image is behind the mirror.
If the height of the image is positive, the image is erect. If the height of the image is negative, then the image is inverted.
It is important to remember that when using the mirror equation, you need to have a common denominator. Make sure that you can solve for the unknown. I go over it in the video and this paper will show you the steps to solve for the variable that you need.
AlgebraforMirrorEquation.pdfPractice the Math
Practice the Math
Click here for the paper that I use in the video. As you watch this video, pause it and try the math on your own. When you have your answer, start the video and see if you are right. It is important to know where YOU make your mistakes so you can correct them for next time!
Remember there are more practice math problems under Chapter 17 Resources. Practice the math and see if your answer matches my answer.
Before the Next Class Period
Before the Next Class Period
Practice these Math Problems Before Class!
Practice these Math Problems Before Class!
Click on the picture to take you to the practice problems that I will be going over the next time we have class. Remember, you need to try the problems on your own to see where you make your mistakes if you want to learn how to do the math problems on your own.
You have finished Lesson 4!
You have finished Lesson 4!
Be sure to head over to google classroom and fill out the exit pass.
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