Energy

صفحه 1:
Energy Energy is a property that enables something to do work Energy has various forms (kinetic, potential, rest energy) Kinetic energy is the energy of a moving object It takes ~1000 N (or ~ 225 lbs) to hit a nail and drive it 5 mm into a surface. 

صفحه 2:
۱ 2 Potential energy is a capacity of doing some 587011 Potential energy is the energy of position Gravitational Potential Energy N = Fd = mgh = PE (potential energy) PE of a 1000-kg car at the top of a 50-m multilevel parking lot is: mgh= (1000 kg)(9.8 m/s2)(50 m)=490 kJ 0 

صفحه 3:
۹ 017 Mass and Energy are related to each other and can be converted into each other. MW slow 4 0111721621 01 115 5. 13 mie? E, (m=1 kg) = 1 kg x (3 10°)? (cm/s)? ~ 1017J PE (m=1 kg, h=9 km) = mgh = 1 kg x 9.8 m/s? x 9000 m ~ 10°J 

صفحه 4:
Energy Transformations Many mechanical processes involve interchanges between KE, PE, and work. Energy exists in some other forms: chemical energy, heat energy, radiant energy, etc. 

صفحه 5:
Conservation of Energy Energy cannot be created or destroyed. It can only be changed from one form to 20 The above statement is called the law of conservation of energy 

صفحه 6:
Chapter 5 Light and Atomic Structure * Light and its properties ¢ Atomic structure * Interaction between Light and Matter * Spectrum 

صفحه 7:
Light in Everyday Life ٠ Light is a form of energy, radiative energy 1 Watt = 1 Joule/sec ۰ Light has color A prism split light into a spectrum (rainbow of colors) ight travels with a speed of c = 300,000 km, 

صفحه 8:
Rainbow 

صفحه 9:
Interaction of Light and Matter Emission Absorption Transmission (passing through) Reflection (scattering) 

صفحه 10:
Properties of Light Light behaves as both a particle anda ۳2۳9 Light particles are called photons, which can be counted individually. Light is also an electromagnetic wave The wavelength is the distance between adjacent peaks of the electric or magnetic field 1 nm (nanometer) = 10° m 1pm (micron) =10*m The frequency is the number of peaks that pass by any point each second, measured in cycles nar canrnnd ar Harts (Lic) 

صفحه 11:
Wavelength is the distance Frequency is the number between adjacent peaks of of waves (cycles) passing the electric field. any point each second. wavelength All light travels with speed c 5 300,000 km/s. Light consists of many individual photons. Each travels at the speed c and can be Prt he A ee pee! Aig DA ee On ‏لي‎ ١ lea a ee eC ‏أجل إن د ملس مل "وشم و‎ 

صفحه 12:
Many Forms of Light The spectrum of light is called the electromagnetic spectrum Different portions of the spectrum are called: The visible light - what we see with our eyes The infrared light - beyond of the red end of rainbow The ultraviolet light - beyond the blue end Radio waves - light with the longest wavelengths X rays - wavelengths shorter than ultraviolet 

صفحه 13:
Electromagnetic spectrum High Frequency Low Frequency ‏ات‎ Curt) ‏ومما‎ MC lu) Pe ere ba ‏تا وكا‎ ir ‏مناد‎ فلا کل 00 ةا 

صفحه 14:
High frequency Short wavelength High quantum energy Low frequency Long wavelength Low quantum energy pereuiu ,سور ‎‘sanem‏ seped SONBMOLOIW N = oO {30} 7 ‏ب كد‎ ‏ع‎ ‎i ‎N ‏ات‎ ‎= ‎i=} ‎lou ‎oO ‎۳ ‏ب‎ 

صفحه 15:
The Sen of light is called Stents spectra of celestial bodies one can learn a wealth of information about them ultraviolel blue green red infrared wavelength 

صفحه 16:
Atomic Structure 92 chemical elements have been identified in the Universe. Nearly 20 more have been created artificially. Each chemical element is made from a different type of atom. Atoms are made from particles called protons, neutrons, and electrons. Protons and neutrons form the nucleus in the center of the atom. Electrons surround the nucleus. 

صفحه 17:
Atomic Structure Positively charged protons are hold together by the strong force, which overcomes electrical repulsion. Negatively charged electrons are attracted to 9 The number of protons in an atom is called the atomic number, which is unique for different chemical elements. The combined number of protons and neutrons in an atom is called the atomic mass number. Atoms of the same element with different 

صفحه 18:
Absorption and Emission in ‏تع‎ ‎nce electrons in atoms can have only specific nergies, the atoms can absorb or release ene nly in these amounts (quanta) lectron gets energy, jumps to an excited sta‘ 2lease the energy, and falls back down The energy is emitted as a photon of light The photon has exactly the same energy tha‘ the electron has lost 

صفحه 19:
Types of Spectra Emission line spectrum consists of photons emitted as each electron falls back to lower levels Absorption line spectrum appears when photons are absorbed, causing electrons to jump ia tan 2 cCornT a produces its own distinct set of spectral lines 

صفحه 20:
Emission by Hydrogen ‎WAS‏ ده ‎ ‎13.6 eV ‎Lya jLyB | Lyy ‎Lyman Lines x ¥ Ground State = Lowest Energy Level ‎ ‎ ‎ ‎ 

صفحه 21:
I 6000 2: )۵( 

صفحه 22:
Examples of Spectra ۱۱ ۱ الال 

صفحه 23:
Thermal Radiation ‘Complex”’ objects - planets, stars, people - roduce thermal radiation Its spectrum depends only on the object’s ۲46۲0۵۵886۵ ‏معمصد غنصه‎ 601 radiation per unit surface area The radiated energy is proportional to the fourth power of the temperature Hotter objects emit photons with a ۱۱۱۱۵۱۱۱۵۹۸ 

صفحه 24:
Temperature and Color 

صفحه 25:
Temperature and Intensity 15,000 K star the Sun (5,800 K) 3,000 K star 103 wavelength (nm) 

صفحه 26:
Reflected light When the light (for example, sunlight) ‏طة ومعاتتاه‎ object (ground, clouds, people), we see only the wavelengths of light that are reflected ferent objects (fruits, rocks, atmospheric ga: lect and absorb light at different wavelength 

صفحه 27:
The Doppler Shift Radial motion of a distant object can be determined due to the Doppler effect ‘Doppler effect causes shifts in the wavelen¢ ۱۶۳ If an object is moving toward us, its entire spectrum is shifted to shorter wavelengths Because shorter wavelengths of the visible light are bluer, the Doppler shift of this object is called a blueshift Cn, NERD ee ‏ا 1 205 ا د‎ ROMAINE I AR CO Ran mS, Yes 7 ee 

صفحه 28:
BLUESHIFT Demo Doppler effect 

صفحه 29:
۸ Spectral information gives us more knowledge about the objects (composition, surface temperature, moving properties) Visible light is only a small portion of the electromagnetic spectrum The Doppler effect tells us how quickly light is moving toward or away from us 

Energy Energy is a property that enables something to do work Energy has various forms (kinetic, potential, rest energy) Kinetic energy is the energy of a moving object mv2 KE = --------2 It takes ~1000 N (or ~ 225 lbs) to hit a nail and drive it 5 mm into a surface. isit www.worldofteaching.com or 100’s of free powerpoints Potential Energy Potential energy is a capacity of doing some work Potential energy is the energy of position Gravitational Potential Energy W = Fd = mgh = PE (potential energy) PE of a 1000-kg car at the top of PE is relative! a 50-m multilevel parking lot is: mgh= (1000 kg)(9.8 m/s2)(50 m)=490 kJ Rest Energy Mass and Energy are related to each other and can be converted into each other. The rest energy of a body is the energy equivalent of its mass. E0 = m0c2 E0 (m=1 kg) = 1 kg x (3 108)2 (cm/s)2 ~ 1017 J PE (m=1 kg, h=9 km) = mgh = 1 kg x 9.8 m/s2 x 9000 m ~ 105 J Energy Transformations Many mechanical processes involve interchanges between KE, PE, and work. Energy exists in some other forms: chemical energy, heat energy, radiant energy, etc. Conservation of Energy Energy cannot be created or destroyed. It can only be changed from one form to another. The above statement is called the law of conservation of energy Chapter 5 Light and Atomic Structure • Light and its properties • Atomic structure • Interaction between Light and Matter • Spectrum Light in Everyday Life • Light is a form of energy, radiative energy 1 Watt = 1 Joule/sec • Light has color A prism split light into a spectrum (rainbow of colors) Light travels with a speed of c = 300,000 km/ Rainbow Interaction of Light and Matter • Emission • Absorption • Transmission (passing through) • Reflection (scattering) Properties of Light Light behaves as both a particle and a wave Light particles are called photons, which can be counted individually. Light is also an electromagnetic wave The wavelength is the distance between adjacent peaks of the electric or magnetic field 1 nm (nanometer) = 10–9 m 1μm (micron) = 10–6 m The frequency is the number of peaks that pass by any point each second, measured in cycles Light is an electromagnetic wave Light consists of many individual photons. Each travels at the speed c and can be Many Forms of Light The spectrum of light is called the electromagnetic spectrum Different portions of the spectrum are called: The visible light - what we see with our eyes The infrared light - beyond of the red end of rainbow The ultraviolet light - beyond the blue end Radio waves - light with the longest wavelengths X rays - wavelengths shorter than ultraviolet Electromagnetic spectrum Electromagnetic spectrum Frequency units – Hertz 1 Hz = 1 c1 Light and Matter The amount of light is called intensity Studying spectra of celestial bodies one can learn a wealth of information about them Atomic Structure 92 chemical elements have been identified in the Universe. Nearly 20 more have been created artificially. Each chemical element is made from a different type of atom. Atoms are made from particles called protons, neutrons, and electrons. Protons and neutrons form the nucleus in the center of the atom. Electrons surround the nucleus. Atomic Structure Positively charged protons are hold together by the strong force, which overcomes electrical repulsion. Negatively charged electrons are attracted to the nucleus. The number of protons in an atom is called the atomic number, which is unique for different chemical elements. The combined number of protons and neutrons in an atom is called the atomic mass number. Atoms of the same element with different Absorption and Emission in Gases nce electrons in atoms can have only specific nergies, the atoms can absorb or release ene nly in these amounts (quanta) Electron gets energy, jumps to an excited stat elease the energy, and falls back down The energy is emitted as a photon of light The photon has exactly the same energy that the electron has lost Types of Spectra Emission line spectrum consists of photons emitted as each electron falls back to lower levels Absorption line spectrum appears when photons are absorbed, causing electrons to jump up in energy Each element or molecule produces its own distinct set of spectral lines Emission by Hydrogen Hydrogen lines in the visible Examples of Spectra Thermal Radiation `Complex’’ objects - planets, stars, people roduce thermal radiation Its spectrum depends only on the object’s temperature Hotter objects emit more total radiation per unit surface area The radiated energy is proportional to the fourth power of the temperature Hotter objects emit photons with a higher average energy Temperature and Color Temperature and Intensity Reflected light When the light (for example, sunlight) strikes an object (ground, clouds, people), we see only the wavelengths of light that are reflected fferent objects (fruits, rocks, atmospheric gas flect and absorb light at different wavelength The Doppler Shift Radial motion of a distant object can be determined due to the Doppler effect e Doppler effect causes shifts in the waveleng light If an object is moving toward us, its entire spectrum is shifted to shorter wavelengths Because shorter wavelengths of the visible light are bluer, the Doppler shift of this object is called a blueshift Doppler Effect Demo Doppler effect Summary Spectral information gives us more knowledge about the objects (composition, surface temperature, moving properties) Visible light is only a small portion of the electromagnetic spectrum The Doppler effect tells us how quickly light is moving toward or away from us