Ms. Ead Physics

1. Ms. Ead Physics S2 Final Review

2. 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

3. 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

4. Transparent, Translucent, and Opaque

5. Angle of reflection Angle of incidence 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.

6. Angle of Incidence Angle of Reflection 1 n1 n2 2 Angle of Refraction 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.

7. 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.

8. The electromagnetic spectrum

9. Mechanical Waves 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

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

11. 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.

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

13. 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

14. 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

15. 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.

16. Resistance The opposition of current flow - measured in Ohms(Ω) Tank (Battery) Faucet (Switch) Pipe (Wiring) What happens to the flow (current) if a rock gets lodged in the pipe? Flow (current) decreases.

17. 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. V=IR R=V/I I=V/R

18. Example: Ohm’s Law • 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? V I R Schematic Diagram IR + - VT = VR

19. Circuit Configuration 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. Components (i.e., resistors, batteries, capacitors, etc.)

20. Example: Series Circuit Solution: Total Resistance: V I R Current Through Each Component:

21. Example: Series Circuit Solution: Voltage Across Each Component: V I R

22. Example: Series Circuit Solution: Verify Kirchhoff’s Voltage Law:

23. Parallel Circuits 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. IT + + + + VR1 VR2 VR3 VT - - - - RT

24. Example Parallel Circuits Solution: Total Resistance: Voltage Across Each Component:

25. Example Parallel Circuits Solution: Current Through Each Component: V I R

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

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

28. 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.