2.3 Lenses Flashcards
What are the properties of an image formed by a diverging lens
Virtual
Upright
Diminished
Properties of the image formed by converging lens beyond 2F and example
Inverted
diminished
Real
Eye
Properties of the image formed by converging lens at 2F
Real
same size
inverted
Properties of image formed between 2F and F and example
Real
Inverted
Enlarged
Projector
Properties of image formed at F
No image formed
Properties of image formed between F and optical centre and example
Virtual
enlarged
Upright
Magnifying glass
Lens equation
1/F = 1/u + 1/v
For a converging lens is F positive or negative
For a diverging lens …
For a real image is v (image distance) + or -
For a virtual image …
Is u (object distance) always + or -
+
What does a graph of 1/v against 1/u look like for a converging lens
Constant slope down
Define focal length
Distance from Focal point to optical centre
Define principal focus
Point on principal axis that parallel rays of light converge or appear to diverge from after refraction
2 equations for magnification m
m = hi/ho
m = v/u
Which lens corrects myopia? Hypermetropia?
Diverging
Converging
Equation for power of a lens
p = 1/f
f = focal length
In a calculation for correcting hypermetropia, what value of u and v are used? Will f be + or -? Why?
u = 0.25
v = original np (- because image is virtual)
+ because converging lens is used
In a calculation for correcting myopia, what values of u and v are used? Will f come out + or -?why?
u = infinity
v = original fp (-)
- because diverging lens is used
Distinguish between a real and a virtual image
Real image is formed by 2 or more real rays of light
Virtual images are formed by both real and virtual rays of light
