What precautions must be taken while conducting the experiment angle of vision of eye?

The size of your pupils actually reflects the state of your body and mind. Pupil size can change because you are fearful, angry, in pain, in love, or under the influence of drugs. Not only does the pupil react to emotional stimuli, it is itself an emotional stimulus. The size of a person’s pupils can give another person a strong impression of sympathy or hostility.

The response of the pupil is an involuntary reflex. Like the knee-jerk reflex, the pupillary response is used to test the functions of people who might be ill or injured. You may have seen a doctor shine light into the eyes of a person with a suspected head injury—they are looking at the pupillary response.

The pupil of your eye is also the source of the red eyes you sometimes see in flash photographs. When the bright light of a camera flash shines directly through the pupil, it can reflect off the choroid, which supplies red blood to the retina (the light-sensitive lining at the back of your eye), and bounce right back out through the pupil. If this happens, the person in the photograph will appear to have glowing red eyes. To avoid this, photographers move the flash away from the camera lens. With this arrangement, the light from the flash goes through the pupil at an angle, illuminating a part of the retina not captured by the camera lens. Many cameras are equipped with red-eye reduction features, such as a pre-flash that causes pupil constriction before the actual flash that illuminates the photo.

This Science Snack is part of a collection that highlights Black artists, scientists, inventors, and thinkers whose work aids or expands our understanding of the phenomena explored in the Snack.

Source: Wikimedia Commons

Dr. Patricia Bath (1942-2019), pictured above, was an ophthalmologist and laser scientist, and was the first woman chair of ophthalmology at a US university. She studied the causes of and cures for blindness, and invented a widely used method of using laser surgery to treat blindness caused by cataracts. Dr. Bath also co-founded the American Institute for the Prevention of Blindness. This Science Snack can help you investigate the structures in the eye that help you see, so you can understand the eye like Dr. Bath did.

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Light - Reflection and Refraction

the precautions are :- 1) Make sure that the pins placed are minimum 4 cm away from each other 2) Make sure the glass slab or prism taken are polished and not broken . 3) Make sure to look at the image through the proper eye level through the glass slab or prism. 4) Sharp lines need to be drawn so that proper result can be observed .

5) Angle of incident ideally should be 45 degrees for better outcome .

1. make sure that you place all the needles/ pins in a straight line
2. the distance between any two pins on the incident ray should be between 3 to 5 cm.

Fix a sheet of white paper on a drawing board with drawing pins. Place the given glass slab nearly in the middle of the sheet.
Mark the boundary of the glass slab with a sharp pencil and label it as PQRS after removing the slab from its position.
On the line PQ mark a point E and draw a normal N1EN2 at it. Draw a line AE making angle AEN1 with the normal.The angle should neither too small nor too large (say about 40 degree).
Now place the glass slab again on its boundary PQRS and fix two pins A and B vertically about 10 cm apart on the line AE (say points A and B).
Look through the glass slab along the plane of the paper from the side SR and move your head until the images of the two pins A and B are seen clearly. Closing your one eye ,adjust the position of your head in such a way that the images of the pins A and B lie in the same straight line.

1.The glass slab should be properly place on white paper 3.The pins should be fixed vertically and should maintain a gap of 5 cm from each other 3.Don't hammer the pins. 4.The feet of pins should be placed in straight line 5.The angle of incidence should lie between 30 and 60 degree.

(i) The glass slab should be perfectly rectangular with all its faces smooth. (ii) While fixing the pins P1 and P2 or the pins P3 and P4, care should be taken to maintain a distance of about 5 cm between the two pins. This would help in tracing the direction of incident ray and that of emergent ray with greater accuracy.