Title Newtons Corpuscular Theory of Light 1 Light

Title: Newton’s Corpuscular Theory of Light 1. Light hits a boundary between glass (n=1. 33) and diamond (n=2. 42) and undergoes refraction. What angle of incidence in the glass would be required to produce an angle of refraction of 14. 0 o in the diamond? 2. A waves is diffracted through a single slit. Under what conditions will the maximum spread of waves? 3. What key assumption is made during the derivation of the equation for the Young double slit experiment? 4. A red laser of wavelength 360 nm is passed through a double slit (slits are 72µm apart) and produces an interference pattern on a screen 6. 5 m away. What is the spacing between the bright fringes in the pattern? 5. A 500 g ball strikes a wall elastically at a speed of 4. 1 ms-1 causing it to reflect back along it’s original path. During the strike it is in contact with the wall for 3. 0 ms. What force does the ball exert on the wall?

Lesson Objectives C-B A-A* A*+ Describe the premise of Newton’s Corpuscular Theory of Light and Huygen’s Wave Theory. Explain what observations led to the acceptance of Newton’s Theory by the rejection of Huygen’s Theory. Explain what observations led to the rejection of Newton’s Theory and resulted in the acceptance of Huygen’s Theory (180 years after it was first suggested).

Independent Research – Group Work C-B Group 1: Newton’s Corpuscular Theory Group 2: Wave Theory Questions to address: • What is the overview of Newton’s Corpuscular Theory of Light? • How was it used to explain sharp shadows? • How did it explain reflection? • How did it explain refraction? • What phenomenon could it not explain? • Why did so many scientists support this theory? • What eventually led to the rejection of this theory? Questions to address: A-A* • What is the overview of Wave Theory? • What key scientists backed Wave A*+ Theory early on? • How did it explain reflection? • How did it explain refraction? • What phenomenon could it not explain? • Why did so many scientists reject this theory? • What eventually led to the acceptance of this theory? As a group, you are to work together to answer these questions. You will present your findings to the class in today’s lesson [5 mins max per group] You may wish to create slides to support your explanations

Title: Determining the Speed of Light 1. A cheetah is moving in a circle with a radius of 4. 65 m. The cheetah’s linear velocity is 2. 40 ms -1. Calculate the cheetah’s angular acceleration 2. In order for an object to be undergoing SHM, what must its acceleration be directly proportional to? 3. A canon located on the ground fires a canon ball at an angle of 43 o to the horizontal at a speed of 80 m/s. How much time later will the canon ball hit the ground? 4. A 1500 kg car travels in a circle around a roundabout. The centripetal force needed to keep the car travelling in the circle is 750 N. What size centripetal force would be needed to keep a 4500 kg tractor travelling around the roundabout at the same speed and radius as the car? 5. State Ohm’s Law.

Lesson Objectives C-B A-A* A*+ Describe the set up that Fizeau used to determine the speed of light and describe the function of each component Describe qualitatively how Fizeau’s experiment could be used to determine the speed of light Derive an expression to determine the actual speed of light from Fizeau’s set up.

Worked Example Determine a value for the speed of light from an experiment like Fizeau’s given that the mirror was positioned 7. 25 km from the wheel, the wheel had 670 teeth and the lowest rotational frequency of the wheel that just blocked the light returning through a gap was found to be 920 rotations per minute.

Title: The Electromagnetic Spectrum 1. What would I expect to register on the meter as I rotated the second filter from its current position through 180 o assuming the source is a transverse wave? 2. Give the order of the EM spectrum from highest to lowest frequency. 3. A radio station broadcasts at a frequency of 93. 4 MHz. What is the wavelength of the signal? 4. A stationary wave is formed on a 3. 0 m string such that there are 6 nodes. What is the wavelength of the progressive wave that created this stationary wave? 5. A transformer with 120 turns on the primary coil and 560 turns on the secondary coil is connected to an AC supply with a maximum EMF of 250 V. If the transformer is 100% efficient, what would we expect the maximum output potential difference to be?

Lesson Objectives C-B Describe the make up of an Electromagnetic wave in terms of oscillating fields and recall the order and key features of the parts of the Electromagnetic spectrum. A-A* Describe how Maxwell’s theory led to his prediction for the speed of Electromagnetic waves in a vacuum and ow this subsequently led to the assumption that light was an Electromagnetic wave. A*+ Explain how Hertz experiment allowed him to measure the speed of Electromagnetic waves (confirming Maxwell’s predictions) and how it led to the confirmation that Electromagnetic waves were indeed transverse.

Worked Example Figure 10 represents a stationary radio wave pattern produced by the superposition of an incident wave emitted from the transmitter and its reflection from a metal sheet. The position of the nodes is determined using a detector moved from the transmitter towards the metal sheet. Distance D takes up 5 nodes and is measured at 3. 72 m. Obtain a value for the speed of the radio waves, given that their frequency is 161 MHz.

Title: Concept of Quanta (Black Body Radiation) 1. Light of wavelength 120 nm is incident on a metal. If the emitted electrons have maximum kinetic energy of 2. 16 x 10 -19 J what is the work function of the metal (in e. V). 2. What is the minimum frequency of photon required to produce and electron-positron pair? 3. Calculate the values of IT, I 1 and I 2 4. What is the size of the reaction for on a stationary block of mass 650 g on a slope of incline 18. 00?

Lesson Objectives C-B Understand that thermal radiation (IR) is an electromagnetic wave and describe the concept of a black body. A-A* Describe Kirchhoff’s experiment to investigate the link between dominant EM wavelength and temperature for a black body and the conclusions he came to. A*+ Explain what ‘ultraviolet catastrophe’ was in the context of classical physics and recognise the part quantum physics had to play in solving it.

Title: Wave-Particle Duality 1. Define the electronvolt. 2. Calculate the final speed of an electron that is accelerated through a potential difference of 4. 6 k. V. 3. Light of wavelength 500 nm is passed through a diffraction grating with 300 lines per mm. How many bright fringes would you expect to see in the diffraction pattern? 4. Describe the relationship between path difference and maxima in the Young double slit experiment. 5. Give one difference and one similarity between emf and potential difference.

Lesson Objectives C-B I can describe the observations that lead to the concept of wave-particle duality. A-A* I can determine the wavelength of a matter wave from its momentum. A*+ I can explain the effect that varying the accelerating p. d will have on the diffraction pattern for electron diffraction.

Worked Example A beam of electrons is emitted from an electron gun and directed at a thin crystal target. Calculate the de Broglie wavelength of the electrons when they have been accelerated by an anode of voltage: a. 2. 5 k. V b. 50 V

Title: The Electron Microscope 1. A capacitor with capacitance 600µF has an initial charge of 100 C. It is discharged through a resistor of 100 kΩ. How long will it take to discharge to 20% of its initial charge? 2. How many electrons will pass a point in a circuit in 1. 0 minutes if a current of 16 m. A is flowing? 3. Sketch the shape and direction of the electric fields between the two parallel plate below: 4. The potential difference across a component is measured to be 2. 7 ± 0. 1 V and the current through it is 0. 8 ± 0. 2 A. What is the resistance of the component (with associated uncertainty)? 5. What is the specific charge o a nucleus of Carbon-14?

Lesson Objectives C-B A-A* A*+ I can describe how a Transmission Electron Microscope (TEM) and a Scanning Tunnelling Microscope (STM) work I can explain the function of each of the lenses in the TEM. I can explain how ‘tunnelling’ electrons allows an STM to scan surfaces of materials.