light and black body radiation Flashcards
what is visible light described as?
electromagnetic waves that cann be detected by the human eye
what does the word incident mean when talking about light?
the point at which the light hits an object
what are all the possible things that can happen if light hits an object
the object can:absorb,reflect or transmit the light
what is reflection by a smooth surface in a single direction called
specular reflection
what is a reflection from a rough surface,where the light is scattered called
a diffuse reflection
all objects are ____
transparent,translucent,or opaque
what does it mean if an object is transparent
the object transmits light coherently,light rays do ot get jumbled,so objects on the other side are clearly seen
what does it mean if an object is translucent
they transmit light but the rays are scattered so objects arent seen clearly through them e.g. frosted glass
what does it mean if an object is opaque
they either reflect or absorb all light incident on them,so no light passes through them.
what happens when all wavlength are reflected equally
the object appears white
what happens when all wavlengths are absorbed
the object appears black
if you look through a coloured filter at an object of the same colour what happens
the object appears as its true colour
what happens if ,for example you view a red and blue object through a red filter?
you will see red and black instead of red and blue due to the blue not being able to pass through the red filter
what happens if you use a green filter to view a red and blue object?
the whole object will appear black due to the colours no t being able to pass through the green filter
all bodies (objects) 1. ______ and 2._____ infrared radiation
- emit
2. absorb
what does the rate an object emits radiation depend on
the nature of the surface and its temperature the hotter the body the faster it emits infrared radiation
what are the features of a perfect black body radiation
it absorbs all of the infrared radiation incident on it
it does not reflect or transmit any infrared radiation
what does the temperature of an object determine
the rate at which it emits radiation
the wavelength of the radiation it emits
as the 1.____increases the amount of 2._____ an object emits at all wavelengths increases but the intensity of 3._____wavelengths increases faster
- temperature
- radiation
- shorter
as an object is heated it first glows 1.__________ as it gets hotter it emits even shorter wavelengths and it becomes 2.______
- red hot
2. whiter
