Chapter 1 Flashcards
What is the equation for the curvature of a circle?
Curvature = 1/r
What are waves are called when they come from a very distant point?
Plane wave-fronts
Light can be thought of as [ ] fronts or [ ]
Wave
Rays
What is the distance between the lens and the focus?
The radius of the wave fronts just after passing through the lens.
Focal Length, f
How much curvature does a converging lens add?
1/f
Lens power (D) =
Lens power (D) = 1 / focal length (m)
1 / v =
1/v = 1/u + 1/f
(Lens maker’s equation)
NB: ‘u’ is negative like on a number line.
Waves from a nearer object are brought together …
beyond the focal point.
The image distance v is [ ] than the focal length f, except for [ ]
greater
very distant objects
What does it mean to magnify?
The size of the image appears larger than the original object.
Linear magnification m =
mage height (m) / Object height (m)
or
Image distance v (m) / Object distance u (m)
What does it mean if the magnification is negative?
The object is inverted
Describe where an image is focused in a digital camera.
light - sensitive microchip called a charge-coupled device (CCD)
What is a CCD?
A screen covered by millions of tiny ‘picture elements’ called pixels
Explain how pixels work
Each pixel stores electric charge when light falls on it - the brighter the light falling on the pixel, the greater the charge stored on it. The image becomes an array of numbers, which can then be manipulated to edit the image.
What is one bit of information?
One pixel simply records ‘high’ or ‘low’, then only one memory location storing a 1 or 0 is needed