To investigate and demonstrate how the different wavelengths of red and blue light differ by finding their focal lengths using a converging lens.
Physics Coursework
Aim
To investigate and demonstrate how the different wavelengths of red and blue light differ by finding their focal lengths using a converging lens.
Apparatus
* Red and Blue LED's (light emitting diodes)
* Wires to connect apparatus together
* Power supply and mains access to control voltage supplied to the LED's
* Ruler in cm and mm
* Converging lens
* Blocks to adjust height of components
Safety
This experiment is relatively safe and there are few hazards. However I will be aware throughout the experiment of the electrical components thus minimising any risk of electric shock.
Although LED's them selves do not get sufficiently hot enough to burn skin the wires may get quite hot if the current passing through them is high enough.
If I conduct the experiment with a high voltage not only may the LED's fuse, the brightness of them may harm my eyes if they are looked at continuously. To reduce this effect I shall have a small voltage but with a high enough brightness within the LED to obtain accurate results.
Chromatic Aberration
Different wavelengths are refracted by different amounts. The refractive index is different for different colours. This leads to an effect called chromatic aberration. A simple lens has different focal lengths at different wavelengths (Colours). This is because the different colours have been refracted through the glass with different amounts. A well made lens therefore will give a sharp image in any single colour but the image will be blurred by the out-of-focus images of all the other colours combined that will have focused at other points beyond the lens. This experiment should show by how much the two extreme visible colours (red and blue) are refracted.
Aim
To investigate and demonstrate how the different wavelengths of red and blue light differ by finding their focal lengths using a converging lens.
Apparatus
* Red and Blue LED's (light emitting diodes)
* Wires to connect apparatus together
* Power supply and mains access to control voltage supplied to the LED's
* Ruler in cm and mm
* Converging lens
* Blocks to adjust height of components
Safety
This experiment is relatively safe and there are few hazards. However I will be aware throughout the experiment of the electrical components thus minimising any risk of electric shock.
Although LED's them selves do not get sufficiently hot enough to burn skin the wires may get quite hot if the current passing through them is high enough.
If I conduct the experiment with a high voltage not only may the LED's fuse, the brightness of them may harm my eyes if they are looked at continuously. To reduce this effect I shall have a small voltage but with a high enough brightness within the LED to obtain accurate results.
Chromatic Aberration
Different wavelengths are refracted by different amounts. The refractive index is different for different colours. This leads to an effect called chromatic aberration. A simple lens has different focal lengths at different wavelengths (Colours). This is because the different colours have been refracted through the glass with different amounts. A well made lens therefore will give a sharp image in any single colour but the image will be blurred by the out-of-focus images of all the other colours combined that will have focused at other points beyond the lens. This experiment should show by how much the two extreme visible colours (red and blue) are refracted.