SOLAR ENERGY

PROPERTIES OF THE SUN

• Distance from the earth 150 000 000 km• Mass 333 400 times the mass of Earth• Consists of Hydrogen and helium• Age 4.6 billion years• Lifespan ~10 billion years• Rotation time 27 days• Surface temperature 5800K• Corona temperature ~1 000 000K

The power of the sun comes from fusion

The energy of the sun and other stars is from fusion, where hydrogen cores fuse together, producing helium.

Every second 600M tons of hydrogen (H) is turned into helium (He). From this 400M tons is turned into energy.

nHeHH 10

42

31

21

Solar energy arrives to Earth as radiation: E=hf

hc

hfE

Black-Body Radiation

All bodies send infrared.

An ideal black body (the Sun, light bulb) absorbs all incoming radiation. This kind of body also emits the same amount of radiation. ( radiative balance)

The hotter the body, the smaller is the wavelenght which is equivalent to the radiations intensity maximum.

With the equivalent wavelength you can determine the temperature of the body:

Wien's displacement law ,λmax=bT

The Black-Body radiation spectrum

As the temperature decreases the peak of the black- body radiation curve moves to longer wavelenghts.The graphs' shape remains.

Max Planck

hfE

Part I An experiment IDeterming the temperature of the

”surface” of the Sun

Idea: •Determine the wavelength corresponding to the maximum intensity of the spectrum of the Sun•Determine the temperature by using Wien's displacement law.

Measured intensity spectrum of the Sun

In Orimattila 24.3.2013

Spectrum of the Sun

Results

(The temperature of sun,s surface)

Part II Photoelectric Effect• Electrons' detachment from

metal caused by electromagnetic radiation

• The smallest frequency, where electromagnetic radiation can detach electrons is called cutoff frequency f0

• If f >f0 =>electrons are detached

• Cutoff frequency depends on the metal

Explanation (Einstein 1905 => Nobel 1921)

• Light consists of photons, the energy of which is

• Photon gives energy to the electrons in the metal, if f > f0

• hf = photons energy• W0= detachment work

• Ek =the maximal kinetic energy of detached electrons

• h = Planck constant 6,62*10-34Js

E

hf

0W

maxkE

max0 kEWhf

hfE

metalli

4,135*10-15eVs

An experiment II:Determining Planck’s constant h

• To determine Planck´s constant h, we measured the diffusion voltages of multicoloured LEDs as a function of frequency.

• The circuit board is equipped with six LEDs in the colours blue, green, yellow and the three different wavelengths of red.

Measurements

Measurement results colour f / in 1014 Hz U0 / V E=eU /J*10-19

465 Blue 6.22 (2.86) Failed result

560 Green 5.16 1.72 2.76

585 Yellow 4.94 1.65 2.64

635 Red #1 4.55 1.51 2.42

660 Red #2 4.38 1.48 2.37

Photoelectric Effect

0

0

maxmax0 ,

WhfeU

eUWhf

eUEEWhf kk

ckxy

f

eUh

0

Planck constant is the slope of the straight line.

For the sake of simplicity, we left *10^-19 and *10^14 from this grid.

Results

Measured:

A light bulb which is powered by a solar cell(Photoelectric effect in practise)

A solar powered toy plane

DictionarySOLAR ENERGY aurinkoenergia GRAPH kaavio, kuvaaja

MASS DEFECT massavaje DISASSEMBLE hajota

BINDING ENERGY

sidosenergia INFRARED lämpösäteily

BLACK-BODY RADIATION

mustan kappaleen säteily

ABSORB imeä

WIEN´SDISPLACEMENT LAW

Wienin siirtymälaki

EMIT lähettää

RADIATION säteily WAVELENGH aallonpituus

PLANCK CONSTANT

Planckin vakio SPECTRUM spektri

PHOTOELECTRIC EFFECT

valosähköilmiö PEAK huippu

AIR-SOURCE HEAT PUMP

Ilmalämpö-pumppu

INTENSITY MAXIMUM

intensiteettimaksimi

CORE ydin CONDUCTION johtuminen

CONSISTANCE pysyvyys STRUCTURAL PARTICLE

Rakennehiukkanen

MEDIUM väliaine CONVECTION Kuljettumine

DETACHMENT irtoaminen PHOTON fotoni

CUTOFF FREQUENCY

rajataajuus KINETIC ENERGY liike-energia

ELECTRIC FIELD sähkökenttä COUNTER VOLTAGE

Vastajännite

SOLAR CELL valokenno APPLICATION sovellus

DICTIONARY• SOLAR ENERGY aurinkoenergia• MASS DEFECT massavaje• BINDING ENERGY sidosenergia• BLACK-BODY RADIATION mustan

kappaleen säteily• VIENNA DISPLACEMENT LAW Wienin

siirtymälaki• RADIATION säteily• PLANCK CONSTANT Planckin vakio• PHOTOELECTRIC EFFECT

valosähköilmiö• AIR-SOURCE HEAT PUMP

ilmalämpöpumppu• CORE ydin• CONSISTANCE pysyvyys

• GRAPH kaavio, kuvaaja• DISASSEMBLE hajota• INFRARED lämpösäteily• ABSORB imeä• EMIT lähettää• WAVELENGHT aallonpituus• SPECTRUM spektri• PEAK huippu• INTENSITY MAXIMUM

intensiteettimaksimi• CONDUCTION johtuminen• STRUCTURAL PARTICLE

rakennehiukkanen• CONVECTION kuljettuminen

• MEDIUM väliaine• DETACHMENT

irtoaminen• CUTOFF FREQUENCY

rajataajuus• PHOTON fotoni• KINETIC ENERGY liike-

energia• ELECTRIC FIELD

sähkökenttä • COUNTER VOLTAGE

vastajännite• SOLAR CELL valokenno• APPLICATION sovellus