Pinhole Experiments
Scott + Harrison
Purpose- To investigate the relationship between object distance
and image height while image distance and object height are constant.
- To investigate the relationship between object height and image height while object distance and image distance are constant
- To investigate the relationship between image distance and and image height while maintaining a constant object height and object distance
- To investigate the effects on the image by increasing the diameter of the pinhole and creating more than one pinholes
Hypothesis- If we decrease the object distance, then the image height
will increase.- If we increase the object height, the image height will
increase- If we increase the image distance, then the object
distance will increase- If we increase the number of pinholes, multiple images will
form- If we increase the diameter of the hole, the image will be
less focused
Equipment/DiagramLight source for holding cards, pinhole camera (a box with
one end open and the other with a translucent screen inside a larger box with one end open and a square hole in the other), arrow cards, meter stick, aluminum foil
Procedure
1. Cover a hole with aluminum foil and poke a hole with a pin in it.2. Face the pinhole at a bright object (not necessarily a lightbulb).3. Set a screen behind the pinhole for the image to be projected on.4. Vary the distance of the object from the pinhole, while keeping the image
distance from the pinhole and object height constant.5. Vary the distance of the screen (thus the image) from the pinhole, while
keeping the object distance and object height constant.6. Vary the height of the object (arrow), while keeping the image distance and
object distance constant.7. Poke some more pinholes and observe the effect.8. Increase the size of a pinhole and observe the effect.
Hi vs Do Hi is proportional to 1/Do
Exp 1 Mathematical Analysis + ErrorExp 1:Image Height-->Hi, Object Distance-->Do, (Di and Ho are held constant)
Hi α 1/DoHi = k*1/Dok = 0.01455m^2 (calc by Logger Pro)
Hi = 0.01455m^2 * 1/Do
hi = h0*di * (1/d0), slope = h0*di = .085 m*.165 m = .01403 m2
Accepted Value= .01403 m2
Experimental Value= .01455 m2
Absolute Error = | Acc-Exp |Absolute Error=| .01403 m2- .01455 m2|Absolute Error= .00052 m2
Relative Error= Abs /AccRelative Error= .00052 m2 / .01403 m2
Relative Error= 3.71%
Hi vs Di
Hi is proportional to Di
Exp 2 Mathematical Analysis + Error
Exp 2:Image Height-->Hi, Image Distance--> Di, (Do and Ho are held constant)
Hi α DiHi = k* Dik = 0.1543m/m (calc by Logger Pro)
Hi = 0.1543m/m * Ho
h0 = .085 m, h0 = .56 mhi = h0/d0* di, slope = h0/d0 = .085 m/.56 m = .1518Accepted Value= .1518Experimental Value= .1543
Absolute Error = | Acc-Exp |Absolute Error=| .1518- .1543|Absolute Error= .0025
Relative Error= Abs /AccRelative Error= .0025 / .1518Relative Error= 1.65%
Hi vs Ho
Hi is proportional to Ho
Exp 3 Mathematical Analysis + ErrorExp 3:Image Height-->Hi, Object Height-->Ho
Hi α HoHi = k* Hok = 0.8527m/m (calc by Logger Pro)
Hi = 0.8527m/m * HoExp 3 Image Height vs Object Heightdi = .165 m, di = .20 m, d0 = .56 m
hi = di/d0 * h0, slope = di/d0 = .165 m/.20 m = .8250
Accepted Value= .8527Experimental Value= .8250
Absolute Error = | Acc-Exp |Absolute Error=| .8250- .8527|Absolute Error= .0277
Relative Error= Abs /AccRelative Error= .0277 / .8250
Relative Error= 3.36%
Similar Triangle Proof
Ray Diagrams
Original
Increasing Object Distance, Decrease Image Height
If we increase the object height, we increase the image height.
All ray diagrams are based on idea that light travels as a straight line.
If we increase the image height, we increase the image distance
Ray DiagramsMultiple Pinholes
Bigger PinholeMultiple Images
Blurred
Animation
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=38.0