Magnifying Lens

• What is the purpose of the video from Cole UK?


  To explain how a convex lens can be used as a magnifying glass and how to calculate magnification
• What should students be able to do by the end of the video?

  Go over a diagram of a convex lens and calculate magnification
• Who is the intended audience for this video?

  Triple physics students
• What happens to the properties of the image when the object is more than two focal lengths from the lens?


  The image is diminished, inverted, and real
• What occurs when the object is between one and two focal lengths from the lens?


  The image is magnified, inverted, and real
• What is the scenario when the object is less than one focal length away from the lens?

  The object is very close to the lens, which is how a magnifying glass works
• How do you draw the ray diagram for a magnifying glass?


  Draw a ray from the top of the object through the center of the lens and another ray parallel to the principal axis that passes through the principal focus
• Why do the rays not meet in the case of a magnifying glass?


  Because the rays only appear to meet when extended behind the lens
• What are the three key properties of the image produced by a magnifying glass?


  The image is magnified, upright, and virtual
• How can you tell that the image is virtual when using a magnifying glass?


  Because the rays do not actually meet at a point
• When does a convex lens produce a virtual image?


  When it is used as a magnifying glass
• What is the formula for calculating magnification?


  Magnification = image height / object height