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PHYSICAL SCIENCE PAPER 1: PHYSICS Electricity and Magnetism ................................................................................................................................................ 2 Fields ............................................................................................................................................................................. 2 Electric Circuits .............................................................................................................................................................. 2 Resistance ..................................................................................................................................................................... 2 Work done or energy transferred.............................................................................................................................. 3 Power dissipated ....................................................................................................................................................... 3 Capacitance ................................................................................................................................................................... 3 Electrodynamics ................................................................................................................................................................ 4 L-H Motor and R-H Dynamo Rule .............................................................................................................................. 4 Dynamo ...................................................................................................................................................................... 4 Alternating Current .................................................................................................................................................... 4 Electromagnetic Radiation ............................................................................................................................................ 5 Nature of an EM wave ............................................................................................................................................... 5 EM Spectrum ............................................................................................................................................................. 5 Photoelectric Effect ................................................................................................................................................... 5 Mechanics ......................................................................................................................................................................... 6 Force, Momentum and Impulse ................................................................................................................................... 6 Momentum ................................................................................................................................................................ 6 Vertical Projectile Motion .......................................................................................................................................... 6 Work, Energy and Power .............................................................................................................................................. 7 Waves, Sound and Light .................................................................................................................................................... 7 The Doppler Effect ........................................................................................................................................................ 7 Mach Numbers .......................................................................................................................................................... 8 Mach Cone ................................................................................................................................................................. 8 2D and 3D Wave Fronts ................................................................................................................................................ 8 Interference ............................................................................................................................................................... 8 Diffraction .................................................................................................................................................................. 8 © Samir Daniels Physical Science Paper 1 Page 1 ELECTRICITY AND MAGNETISM FIELDS ๏ท ๏ท ๏ท A field is a region of space in which an object experiences a force o Force is equal to the product of electric field strength and the charge in the field. o ๐น = ๐ธ๐ A point charge goes from positive to negative o Field lines are drawn to describe what a positive charge will do. An electric field (๐ธ) exists due to the presence of just one charge. o ๏ท ๐ฃ ๐ธ=๐ ๏ง Measured in ๐๐ถ โ1 ๏ง ๐ = 9 × 109 ๏ง ๐ is the distance ๏ง ๐ is the charge on the charge sphere Adding another charge in the field will experience a force o ๏ท ๐๐ ๐2 ๐ธ= ๐๐1 ๐2 ๐2 ๐น= Coulombโs Law: the force of an electric force is directly proportional to the product of two charged particles and inversely proportional to the square of the distance between the two of them. ELECTRIC CIRCUITS ๏ท Current is the push of electrons o ๏ท ๐ผ= ๐ ฮ๐ก Electric Current Strength is the number of coulombs passed in a second ๐ = ๐ผ๐ o ๐๐๐ = ๐ผ(๐ + ๐) ๐ ๐ก๐๐ก = ๐ + ๐ RESISTANCE ๏ท ๏ท ๏ท ๏ท ๏ท Ohmโs Law: The resistance in a circuit is directly proportional to the potential difference and inversely proportional to the current flowing through the circuit, provided that the temperature is constant. Ohmic Conductors are those which follow Ohmโs Law (๐ = ๐ผ๐ ) o Copper wire Non-ohmic conductors are those which donโt obey Ohmโs Law o Transistors ๐ ๐ ๐๐๐๐๐ = ๐ 1 + ๐ 2 + ๐ 3 + โฏ 1 ๐ ๐๐๐๐๐๐๐๐ = 1 ๐ 1 1 +๐ 2 + 1 ๐ 3 +โฏ Remove Resistor Voltage Current Parallel Series Voltage Same Voltage Splits Current Splits Current Same Add Resistor Voltage Current Series Parallel © Samir Daniels Physical Science Paper 1 Page 2 WORK DONE OR ENERGY TRANSFERRED o ๐ = ๐๐ = ๐๐ผ๐ฅ๐ก = ๐ผ 2 ๐ ๐ฅ๐ก = ๐ 2 ๐ฅ๐ก ๐ POWER DISSIPATED o ๐ = ๐ ๐ฅ๐ก = ๐๐ผ = ๐ผ 2 ๐ = ๐2 ๐ measured in W CAPACITANCE ๏ท Measured in Farads ๏ท ๐ถ= ๏ท ๐0 ๐ด ๐ o o o ๐0 = 8.85 × 10โ12 Permittivity of free space ๐ด is the area of the plates ๐ is the distance between the plates o o A dielectric (insulator) is in between the plates o Capacitance in Series o o 1 ๐ถ๐ก๐๐ก 1 1 1 2 =๐ถ +๐ถ +โฏ ๏ท Capacitance in Parallel ๏ท o o ๐ถ๐ก๐๐ก = ๐ถ1 + ๐ถ2 + โฏ Charge (๐) o ๐ถ= ๐ ๐ © Samir Daniels Physical Science Paper 1 Page 3 ELECTRODYNAMICS L-H MOTOR AND R-H DYNAMO RULE ๏ท Left Hand Motor ๏ท o Right Hand Dynamo o Flemming ๏ท ๏ท o AC produced โ generator uses a SLIP RING DC produces โ generator uses a SPLIT RING DYNAMO ALTERNATING CURRENT ๏ท ๏ท ๏ท ๐ผ๐๐๐ฅ โ2 ๐ ๐๐๐๐ = ๐๐๐ฅ โ2 ๐ผ๐๐๐ = Average power in an AC Circuit o 2 ๐๐๐ฃ๐๐๐๐๐ = ๐๐๐๐ × ๐ผ๐๐๐ = ๐ผ๐๐๐ ×๐ = 2 ๐๐๐๐ ๐ © Samir Daniels Physical Science Paper 1 Page 4 ELECTROMAGNETIC RADIATION NATURE OF AN EM WAVE ๏ท ๏ท ๏ท The source of electromagnetic waves โ accelerating charge The EM wave propagates1 when an electric field produces a magnetic field oscillating in a pale at right angles to oscillating electric field. Speed of EMR = 3 × 108 ms-1 = c EM SPECTRUM ๏ท ๐ = ๐๐ Big wavelength Small frequency Radio Waves Microwaves Infrared Visible Light Red Orange Yellow Green Blue Indigo Violet Ultraviolet X-ray Small Wavelength High frequency Gamma PHOTOELECTRIC EFFECT ๏ท The process that occurs when light shines on a metal and it ejects an electron o Energy of a photon = ๐ธ = โ๐ = ๏ง ๏ง ๏ท โ๐ = ๐0 + โ๐ ๐ Planckโs Constant (โ) = 6.63 × 10โ34 ๐ฝ๐ Speed of light (๐) = 3 × 108 ๐๐ โ1 1 ๐๐ฃ 2 2 ๏ท ๏ท 1 Spreads © Samir Daniels Physical Science Paper 1 Page 5 MECHANICS FORCE, MOMENTUM AND IMPULSE MOMENTUM ๏ท ๏ท ๏ท Motion of a moving body is measured by the product of its mass and velocity o ๐ = ๐๐ o kgโmโs-1 The momentum of a system is conserves when no external forces act upon it External forces cause momentum to change (Impulse) ๐๐ = ๐ญ๐๐๐ ๐๐ o ๏ท ๐น๐๐๐ก = ฮ๐ ฮ๐ก o The longer something takes to happen, the less force it has Momentum is conserved in a closed system o Kinetic energy is transferred from one to the other o Inelastic collisions occur when two objects collide and do not bounce away from each other. Momentum is conserved. Kinetic energy is not conserved. ๏ง ๐๐๐๐๐๐๐ = ๐๐๐๐ก๐๐ ๏ฎ ๐๐ ๐ฃ๐๐ + ๐๐ ๐ฃ๐๐ = ๐๐+๐ ๐ฃ๐ o ๏ฎ ๐๐ โ mass of ๐ ๏ฎ ๐ฃ๐๐ โ initial velocity of ๐ ๏ฎ ๐๐+๐ โ mass of ๐ and ๐ (combined mass) ๏ฎ ๐ฃ๐ โ final velocity of combined mass Elastic collisions occur when the objects bounce off each other after the collision. Both momentum and kinetic energy are conserved ๏ง ๐๐๐๐๐๐๐ = ๐๐๐๐ก๐๐ ๏ง ๏ฎ ๐๐ ๐ฃ๐๐ + ๐๐ ๐ฃ๐๐ = ๐๐ ๐ฃ๐๐ + ๐๐ ๐ฃ๐๐ Kinetic energy is also conserved, so ๐พ๐ธ๐ = ๐พ๐ธ๐ ๏ฎ 1 ๐ ๐ฃ2 2 ๐ ๐๐ 1 1 1 2 + 2 ๐๐ ๐ฃ๐๐ = 2 ๐๐ ๐ฃ๐2 + 2 ๐๐ ๐ฃ๐2 VERTICAL PROJECTILE MOTION ๏ท ๏ท ๏ท Draw a Diagram! ๐ = 9.8ms-2 (decide whether up or down is positive) Write down what you know / what information is given and what you need to find out. o ๐ฃ๐ = ๐ฃ๐ + ๐ฮ๐ก 1 2 o ฮ๐ฅ or ฮ๐ฆ = ๐ฃ๐ ฮ๐ก + ๐ฮ๐ก 2 o ๐ฃ๐2 = ๐ฃ๐2 + 2๐ฮ๐ฅ or ฮ๐ฆ o ฮ๐ฅ or ฮ๐ฆ = ( ๐ฃ๐ +๐ฃ๐ ๏ง ๏ง 2 ) ฮ๐ก Use ฮ๐ฅ for horizontal motion Use ฮ๐ฆ for vertical motion © Samir Daniels Physical Science Paper 1 Page 6 Newtonโs First Law: An object will remain at rest or at a constant speed unless an external force acts upon it. Newtonโs Second Law: The net force acting on an object is equal to the rate of change in momentum ๐น๐๐๐ก = ฮ๐ ฮ๐ก Newtonโs Third Law: when objects interact with each other, the exert forces that are equal in size but opposite in direction to each other. F ORCE F ORMULAE ๐น๐๐๐ก = ๐๐ ๐น๐๐๐ก = ๐ฅ๐ = ๐๐ฃ๐ โ ๐๐ฃ๐ ๐ = ๐๐ฃ ๐ค = ๐๐ WORK, ENERGY AND POWER ๏ท ๏ท ๐ = ๐นฮ๐ฅ cos ๐ o Work done on an object when a force is applied at an angle will cause the object to move a distance. ๐พ๐๐๐ = ๐ซ๐ฌ๐ = ๐ฌ๐๐๐๐๐๐ โ ๐ฌ๐๐๐๐๐๐๐๐ ๏ท ๐๐ธ = ๐ธ๐ + ๐ธ๐ ๏ท ๐ ๐ด๐ฌ = ๐๐๐ + ๐๐๐ ๐ Power is the rate at which work is done o ๐ = ๐น๐ฃ WAVES, SOUND AND LIGHT THE DOPPLER EFFECT The apparent change in frequency and wavelength of a wave when the observer and the source of the wave more relative to each other ๐๐ณ = ๏ท ๏ท ๐ + ๐๐ณ × ๐๐บ ๐ + ๐๐บ o ๐๐ฟ โ the frequency of the sound heard by the listener o ๐ฃ โ velocity of the waves o ๐ฃ๐ฟ โ velocity of the listener o ๐ฃ๐ โ velocity of the source o ๐๐ โ frequency of the source IMPORTANT o Source moves toward listener ๐ฃ๐ negative o Source moves away from listener ๐ฃ๐ positive o Listener moves toward source ๐ฃ๐ฟ positive o Listener moves away from source ๐ฃ๐ฟ negative o Source coming toward you โ higher sound, increased pitch o Source moving away from you โ lower sound, decreased pitch Frequency is measured in Hz © Samir Daniels Physical Science Paper 1 Page 7 MACH NUMBERS The ratio between the speed of an object and the speed of sound ๐ด๐๐๐ ๐ต๐๐๐๐๐ = ๐๐๐๐๐๐๐ ๐๐๐๐๐๐ MACH CONE ๐ฌ๐ข๐ง ๐ฝ = ๐๐๐๐๐๐ ๐๐๐๐๐๐๐ 2D AND 3D WAVE FRONTS Huygenโs Principle โ each wavefront acts like appoint source of circular waves. They interfere to form another wavefront A Wave front is an imaginary line that connects waves that are in phase. INTERFERENCE Constructive Interference when both waves have displacement in the same direction Deconstructive interference when waves have displacement in opposite directions DIFFRACTION ๏ท 1 Slit o © Samir Daniels Physical Science Paper 1 Page 8 ๏ท 2 Slits ๏ท o 2 sources o ๏ท Slit diffraction pattern ๏ท ๐ฌ๐ข๐ง ๐ฝ = o o o o ๐๐ ๐ ๐ is the angle to the minimum ๐ is the order of the minimum (e.g. ± 1, ±2, ±3) ๐ is the wavelength of the waves ๐ is the width of the slit (in meters) © Samir Daniels Physical Science Paper 1 Page 9