Ms. Ead Physics S2 Final Review

Light vs. Sound waves Light travels a lot faster than sound: Speed of light in air = 300,000,000 meters per second Speed of sound in air (at 0 Celsius) = 331 meters per second Light can travel in empty space …Sound can’t because sound is the compression of the medium For sound traveling in air, sound wave is made of variations in the pressure of the air Sound Waves Travel As Variations in Pressure

Light vs. Sound waves Light is a transverse wave: Transverse means that the wave travels perpendicular to the displacement Sound is a compression wave The wave travels in the same direction as the displacement

Transparent, Translucent, and Opaque

Reflection Reflection – wave strikes a surface and is bounced back. Law of Reflection: angle of incidence = angle of reflection Assumes smooth surface. Measured from normal. Angle of incidence Angle of reflection

Snell’s Law: As light waves pass from one medium to another, they also change direction. As a wave passes from low n to high n, it bends toward the normal. As a wave passes from high n to low n, it bends away from the normal. If n is the same for both media, the wave does not bend. Angle of Incidence Angle of Reflection Angle of Refraction 1 2 n1 n2

Refraction change in direction of propagation of any wave as a result of its traveling at different speeds at different points along the wave front.

The electromagnetic spectrum

Mechanical waves can be transverse or compressional Waves that need matter (medium) to transfer energy like sound waves, ocean waves, ripples in water, earthquakes, wave of people at a sporting event. Mechanical waves can be transverse or compressional

Parts of a Transverse Wave The wavelength is the horizontal distance, either between the crests or troughs of two consecutive waves.

Compressional Wave (longitudinal) A mechanical wave in which matter in the medium moves forward and backward along the same direction that the wave travels like sound waves.

Electricity Invisible force that provides Movement of electrons Invisible force that provides light, heat, sound, motion . . .

Conductors and Insulators Electrons flow easily between atoms 1-3 valence electrons in outer orbit Examples: Silver, Copper, Gold, Aluminum Electron flow is difficult between atoms 5-8 valence electrons in outer orbit Examples: Mica, Glass, Quartz

Current The flow of electric charge - measured in AMPERES (A) Tank (Battery) Faucet (Switch) Pipe (Wiring) When the faucet (switch) is off, is there any flow (current)? NO When the faucet (switch) is on, is there any flow (current)? YES

Voltage The force (pressure) that causes current to flow - measured in VOLTS (V) Tank (Battery) Faucet (Switch) Pipe (Wiring) When the faucet (switch) is off, is there any pressure (voltage)? YES – Pressure (voltage) is pushing against the pipe, tank, and the faucet. When the faucet (switch) is on, is there any pressure (voltage)? YES – Pressure (voltage) pushes flow (current) through the system.

Resistance The opposition of current flow - measured in Ohms (Ω) Tank (Battery) Faucet (Switch) Pipe (Wiring) All materials have resistance. Conductors have little resistance. Insulators provide a lot of resistance. Some electronic components (resistors) have a specific resistance. These are often needed to reduce current in order to protect other components or to adjust the amount of current that goes to other components. What happens to the flow (current) if a rock gets lodged in the pipe? Flow (current) decreases.

V=IR I=V/R R=V/I Ohm’s Law Current in a resistor varies in direct proportion to the voltage applied to it and is inversely proportional to the resistor’s value The mathematical relationship between current, voltage, and resistance If you know 2 of the 3 quantities, you can solve for the third. Quantities Abbreviations Units Symbols Voltage V Volts Current I Amperes A Resistance R Ohms Ω V=IR I=V/R R=V/I

Example: Ohm’s Law Circuit Theory Laws Digital Electronics TM 1.2 Introduction to Analog The flashlight shown uses a 6 volt battery and has a bulb with a resistance of 150 . When the flashlight is on, how much current will be drawn from the battery? VT = + - VR IR Schematic Diagram V I R Project Lead The Way, Inc. Copyright 2009

Circuit Configuration Circuit Theory Laws Digital Electronics TM 1.2 Introduction to Analog Components in a circuit can be connected in one of two ways. Parallel Circuits Both ends of the components are connected together. There are multiple paths for current to flow. Series Circuits Components are connected end-to-end. There is only a single path for current to flow. Overview of series and parallel component configuration. Components (i.e., resistors, batteries, capacitors, etc.) Project Lead The Way, Inc. Copyright 2009

Example: Series Circuit Circuit Theory Laws Example: Series Circuit Digital Electronics TM 1.2 Introduction to Analog Solution: Total Resistance: Current Through Each Component: V I R This slide provides the solution. If you print handouts, don’t print this page. (1 of 3) Project Lead The Way, Inc. Copyright 2009

Example: Series Circuit Circuit Theory Laws Example: Series Circuit Digital Electronics TM 1.2 Introduction to Analog Solution: Voltage Across Each Component: V I R This slide provides the solution. If you print handouts, don’t print this page. (2 of 3) Project Lead The Way, Inc. Copyright 2009

Example: Series Circuit Circuit Theory Laws Example: Series Circuit Digital Electronics TM 1.2 Introduction to Analog Solution: Verify Kirchhoff’s Voltage Law: This slide provides the solution. If you print handouts, don’t print this page. (3 of 3) Project Lead The Way, Inc. Copyright 2009

Parallel Circuits Characteristics of a Parallel Circuit Circuit Theory Laws Parallel Circuits Digital Electronics TM 1.2 Introduction to Analog Characteristics of a Parallel Circuit The voltage across every parallel component is equal. The total resistance (RT) is equal to the reciprocal of the sum of the reciprocal: The sum of all of the currents in each branch (IR1 + IR2 + IR3) is equal to the total current (IT). This is called Kirchhoff’s Current Law. Characteristics of a parallel circuit. + - VR1 VR2 VR3 RT VT IT Project Lead The Way, Inc. Copyright 2009

Example Parallel Circuits Circuit Theory Laws Example Parallel Circuits Digital Electronics TM 1.2 Introduction to Analog Solution: Total Resistance: This slide provides the solution. If you print handouts, don’t print this page. (1 of 3) Voltage Across Each Component: Project Lead The Way, Inc. Copyright 2009

Example Parallel Circuits Circuit Theory Laws Example Parallel Circuits Digital Electronics TM 1.2 Introduction to Analog Solution: Current Through Each Component: V I R This slide provides the solution. If you print handouts, don’t print this page. (2 of 3) Project Lead The Way, Inc. Copyright 2009

Electrical Power Electrical power is directly related to the amount of current and voltage within a system. Power is measured in watts

Nuclear Fission The action of dividing or splitting something into two or more parts.

Nuclear Fusion Nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles and releasing energy. Hydrogen conversion into helium on the sun through the process of fusion generates the Sun’s intense energy.