Tag Archives: refraction
Pins inside and outside of beaker filled with water – 2012 sciphy practical
A pin in the beaker of water appears higher than its actual position due to refraction of light.
In this experiment, you have to adjust the pin at the cork to a suitable height, such that the pin and the image of the pin inside the beaker of water is aligned and that ‘pins at position of no parallax’ position.
The video below guides you in adjusting the height of the pins to locate correct height.
Similar kind of experiment: Pins with Lens and mirror
Light Experiments – Glass Block and Pins
The video include 3 different light experiments which involve glass block and pins.
Most students faced difficulties in locating the pins through the glass block. It is important to close one eye and use your master eye to view.
Hope this video helps!
In experiments like this, the sources of error include:
– the holes created by the pins are too big, hence the line drawn using the two holes may not be very precise, hence affecting the distance/angle measured (depends on experiments)
– When putting back the glass block back on the paper, the position may be not exactly the same, hence affecting the angle/distance measured.
As a precaution, it is good to ensure that the distance between the two pins are more than 4 – 5 cm. With the holes further apart, the line drawn will be more accurate.
Demonstration of Reflection, Refraction and TIR using light source with a slit
Reflection of light using a mirror
Refraction of light using various shaped optical mediums
Total Internal Reflection (TIR) using a semi-circular perspex
For Total Internal Reflection (TIR) to occur:
1) angle of incidence i is greater than the critical angle c
2) the light is travelling from an optically denser medium towards a less dense medium
To bend or not to bend?
Important concepts:
1) angle of incidence is the angle between the incident ray and normal
2) when the angle of incidence i = 0, light will pass through without bending
Refraction of Light
Refraction of Light in Glass Block
Refraction is the bending of light as light travels from one medium to another medium of different refractive index.
As light travels from less dense medium (air) to the denser medium (glass), it bends towards the normal as the speed of light decreases in the medium.
The video below show how the refraction takes place in the glass block and how to position the needles in line.
<p>Refraction of Light – Glass Block + Needles from evantoh on Vimeo.</p>
Refraction
This is not magic! As both the water and crystal balls have the same refractive index (optical density), light will pass through without bending as if both are of the same medium. Hence you are not able to see the crystal balls.
Evan's Space 