PAG 06.2 Experiments With Light Flashcards
What is refraction?
Refraction is the changing of speed of a wave as it passes into a new medium of a different optical density
What quantity doesn’t change when light undergoes refraction?
Frequency remains constant when a wave undergoes refraction
What happens when light enters a more optically dense medium?
Refraction will occur. The light will slow down, the wavelength will decrease and the light will bend towards the normal
Suggest a suitable light source to investigate refraction through a glass block
A ray box can be used to produce a thin Bea, of light suitable for investigating refraction. This has a lower risk than a laser
What is the risk of using a laser to investigate refraction through a glass block?
The glass block may reflect some of the light and this could enter the eye and cause damage
How can the angle of refraction be measured in this experiment?
Draw around the glass block. Mark the ray entering and leaving the block and then remove the block. Connect the two lines with a straight line and measure the angle that this line makes with the normal
Describe the path of the light when it enters the glass block along the normal
The light will continue travelling in a straight line through the block
How can the refractive index be obtained from a graph of sin(I) against sin(r)?
n=sin(I)/sin(r)
Refractive index is the gradient
What is the critical angle?
The angle of incidence for which the angle of refraction is 90*
What occurs beyond the critical angle?
When angle of incidence exceeds critical angle, light will undergo total internal reflection
How can the refractive index of the glass block be determined from the critical angle?
n=1/sin(c)
What safety precautions should be taken when using a ray box?
The bulb and surrounding metal parts can become very hot. Allow it to cool after use, avoid touching metal regions and switch it off when it is not being used. Never look directly into the light
