# Dual Nature Of Radiation And Matter Class 12 Notes Physics Chapter 11 - CBSE

## What are Dual Nature Of Radiation And Matter ?

 Topic Name Formula Symbol Representation Important Points Photon Theory of Light E = hv=(hc/λ)jouleor E =(hc/λ)=(1240/λ)eVnm E = Energy of photon,h = Planck’s constant,v = Frequency of photonc = Speed of lightλ = Wavelength of photone = Charge of electron Packets of energy which are emitted by source of radiation they travelled in straight line.The rest mass of photon is zeroFrequency of photon does not change when it passes through different medium but its wavelength change.Momentum of photon is (hv/c) or (h/λ) Intensity of Light I =(E/At)=(P/A) I = Intensity of lightE = Incident energyt = Time takenA = Area of surfaceP = Power of source Energy of light passing through per unit area of a surface per unit time is known as intensity of light.When radiation of suitable wavelength or frequency is incident on a metal, electrons are ejected. This effect is known as photoelectric effect.Photoelectric effect varifies quantum nature of light.Photoelectric effect is based on the law of conservation of energy.Alkali metals, like lithium, sodium, potassium, caesium etc. show photo electric effect with visible light. Work Function Φ=hvΦ=(hc/λ0) Φ = Work functionh = Planck’s constantVo = Threshold frequencyλo = Threshold wavelength The minimum energy of the incident photon below which these will be no ejection of photoelectrons from a metal surface, is known as work function or threshold energy for that metal.
 Topic Name Formula Symbol Representation Important Points Einstein’s equation of photoelectric effect hv = kmax + Φ0orkmax = h – Φ0orev0 = hv – hv0 h = Planck’s constant v = Frequency of the incident photonkmax = Maximum kinetic energy of ejected electronsΦ0 = Work function of the metalU0 = Stopping potential V0 = Threshold frequencye = Charge on electron • According to Einstein, photon energy is utilized for two purposes, partly for getting the electrons free from the atom and away from the metal surface known as the work function of the metal (Φ0) and the remaining photon energy is used up in providing the electrons kinetic energy of (1/2)mv2 de-Broglie Hypothesis of Matter Waves λ=(h/p)=(h/mv)=(h/√2mE) λ = de-Broglie wavelength or wavelength associated with particle p = momentum of the particle m = mass of the moving particle v = velocity of the moving particle E = kinetic energy of the moving particle • According to de-Broglie hypothesis, a moving particle sometimes acts as a wave and sometimes as a particle. The wave associated with waving particle is called matter waves or de-Broglie waves.