black body curves and wien's law — VCE physics year 11, live

Black body curves and Wien's law

Every object above absolute zero emits electromagnetic radiation across a spread of wavelengths, and for an ideal emitter (a black body) the shape of that spread depends only on temperature. As the object gets hotter, its curve rises at every wavelength, its peak moves to a shorter wavelength (Wien's law: λmaxT = 2.898 × 10⁻³ m K) and the total energy it radiates, the area under the curve, grows very steeply. This is the real knowscape from knowhere, not a picture of one. Drag it. Watch what actually changes.

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why this one carries the topic.

Thermal energy is stored in how particles move and sit; heat is that energy moving hot to cold. Conduction and convection need matter; radiation does not: it is electromagnetic waves, light's family. Hotter things radiate more at shorter wavelengths, and absorbed radiation warms things again.

Changing the temperature redraws a glowing object's black body curve against wavelength, beside the Sun's 5800 K curve, across shaded ultraviolet, visible and infrared regions. The peak slides along Wien's path to shorter wavelengths as the curve and its area grow; one toggle works λmax live, the other splits the area into UV, visible and infrared shares.

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A black body curve plots the energy an object emits against wavelength; its shape is set by the object's temperature alone.

Wien's law: λmaxT = 2.898 × 10⁻³ m K, with T in kelvin, so doubling the temperature halves the peak wavelength.

The Sun is close to a 5800 K black body: it peaks near 500 nm and emits mainly infrared (about 51%), visible (37%) and ultraviolet (12%) radiation.

A hotter object emits more at every wavelength, so its curve sits wholly above a cooler one's and the area under it is much larger.

Total energy radiated rises steeply with temperature (in proportion to T⁴), so doubling the kelvin temperature gives 16 times the energy.

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this conceptblack body curves and wien's lawChanging the temperature redraws a glowing object's black body curve against wavelength, beside the Sun's 5800 K curve, across shaded ultraviolet, visible and infrared regions.

sits under itmaxwell and electromagnetic wavesbecause The curve spans ultraviolet, visible and infrared, so the electromagnetic spectrum needs to be familiar first.

sits under itwave graphs against time and distancebecause Reading wavelength off a wave makes the horizontal axis of the curve meaningful.

sits under itparticle model of temperature and heatbecause Wien's law needs temperature in kelvin, which comes from the particle model of temperature.

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dispersion of white light in a prismin the appparticle model of temperature and heatin the appheating curve and latent heatin the appgreenhouse effect and earth's energy balancein the apptransverse and longitudinal wavesin the appwave graphs against time and distancein the appreflection and refraction at a boundaryin the app

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