Conceptual Physics - Semester 2 Final Review

UNIT 5, PART 1: ELECTROSTATICS

Conductors vs. Insulators:
- A conductor is a material that allows for the free movement of charges.
- An insulator is a material that does not allow for the free movement of charges.
Electric Force and Charge/Distance:
- If the strength of one of the charges is doubled, the electric force between the charges would double.
- If the distance between the two charges is doubled, the electric force between the charges would be quartered because the force is inversely proportional to the square of the distance ( $F \propto \frac{1}{r^2}$ ).
Arrangement of Charges:
- To solve these questions you would need to:
  - Draw a free body diagram for the center charge.
  - Consider the direction the center charge would move and explain your reasoning.

Static Electricity

Classic Experiment with Balloon and Hair:
- Rubbing a balloon on a person’s hair generates static electricity, causing the hair and the balloon to attract each other.
- Rubbing the balloon on hair is necessary to generate static electricity because it transfers electrons from the hair to the balloon, charging them.
Balloon and Paper:
- The balloon can pick up pieces of paper because of the arrangements of charges on the balloon and paper that allows the balloon to pick up pieces of paper.
- A dipole is a molecule with a positive and negative end, like water.
Charged Glass Rod and Van de Graaff Generator:
- When a positively charged glass rod touches an uncharged Van de Graaff generator, electrons from the generator will flow to the rod until equilibrium is reached.
- If the rod was not touching the generator, there would be no flow of charges because there is no direct contact or path for charge transfer.

UNIT 5, PART 2: CIRCUITS

Series vs. Parallel Circuits:
- Series Circuit: Components are connected along a single path, so the same current flows through each component. The total resistance is the sum of individual resistances.
- Parallel Circuit: Components are connected across multiple paths, so the voltage is the same across each component. The total resistance is less than the smallest individual resistance.
Circuit Calculations:
- Total Resistance: Calculate the total resistance of the circuit.
- Current Flow: Determine how much current flows through the circuit.
- Power Generation: Calculate how much power the circuit generates.
Table Completion:
- Resistors in Series: Total resistance is the sum of individual resistances ( $R{total} = R1 + R_2$ ).
- Resistors in Parallel: Total resistance is calculated using the formula $\frac{1}{R{total}} = \frac{1}{R1} + \frac{1}{R2}$ , which can be simplified to $R{total} = \frac{R1 \cdot R2}{R1 + R2}$ for two resistors.

Circuit Diagrams

Circuit Diagrams with Resistors in Series and Parallel
Voltage and Current Calculations:
- Ohm's Law: Use Ohm's Law ( $V = IR$ ) to find the voltage across and current through each resistor in both series and parallel circuits.
Parallel Resistors with Same Resistance:
- If a circuit contains two resistors in parallel ( $R1$ and $R2$ ) with the same resistance ( $R$ ), the total resistance ( $R_{total}$ ) is always less than the resistance of the individual resistors.
 - This can be shown mathematically: $\frac{1}{R{total}} = \frac{1}{R} + \frac{1}{R} = \frac{2}{R}$ so $R{total} = \frac{R}{2}$ .
Complex Circuit Analysis:
- Determine the total resistance and current through each resistor when a switch is open and closed. The opening or closing of the switch would change the structure of the circuit.

Current Source and Resistor Lab

Resistance from Slope
- The student used a current source in a circuit with a resistor and measured the voltage across the resistor. Use the slope of the best fit line to estimate the resistance of the resistor (careful with units!).
- $R = \frac{V}{I}$
Data Prediction
- Draw on the graph what data you would expect if the resistor had half the original resistance.
- Draw on the graph what data you would expect if the resistor had twice the original resistance.

UNIT 7-1: WAVES (BASICS)

Transverse vs. Longitudinal Waves:
- Transverse Wave: The particles' motion is perpendicular to the wave's direction.
- Longitudinal Wave: The particles' motion is parallel to the wave's direction.
Wave Properties:
- Amplitude: The maximum displacement of the wave from its equilibrium position.
- Wavelength: The distance between two consecutive crests or troughs.
- Frequency: If both waves were traveling at a velocity of 25 m/s, calculate the frequency of each wave using the formula $v = f \lambda$ .
  - $v$ = velocity
  - $f$ = frequency
  - $\lambda$ = wavelength
Mechanical Waves
- Consider raindrops falling on a puddle of water on the ground.
  - Determine if the waves that are produced transverse or longitudinal.
  - Draw a picture explaining your reasoning.
Wave Energy and Amplitude
- The drops of water have more energy due to their higher mass. How would the wave produced by the raindrop hitting the water be different, and how does this show that the rain does in fact have more energy?
Graphing Wave Properties
- Given a mechanical wave with an amplitude of 5 meters and a frequency of 2 Hz, traveling at a velocity of 12 meters per second.
Amplitude vs. Time Graph
- Create an amplitude vs. time graph with the information provided (Label axes).
Wave Interference
- Suppose a second wave with an amplitude of 3 meters and the same frequency interacts with the first wave. Draw an amplitude vs. time graph for a wave that:
  - Constructively interferes with the first wave.
  - Destructively interferes with the first wave.
Resulting Wave Appearance
- If one wave were to interfere with the original wave, illustrate what the resulting wave would look like.

UNIT 7-2: SOUND WAVES

Sound Wave Properties:
- In a sound wave, the frequency represents the wave’s pitch, and the amplitude represents its loudness.
Standing Waves:
- Draw a standing wave for these three scenarios and state how the wavelength of the wave relates to the length of the pipe/string:
  - A pipe that is open on both ends.
  - A pipe that is open on one end and closed on another.
  - A string that is vibrating.
Vibrating String Calculation
- A string with a length of 60 cm is plucked.
  - Draw a picture of the string vibrating, and label the nodes and antinodes.
  - Calculate the wavelength and frequency of the sound produced, assuming the speed of sound is 343 m/s.
Brass Instruments
- Brass instruments, like trumpets and trombones, use a system of buttons and valves to produce musical notes.
  - Identify what mode of standing wave is produced when played.
  - Given the trumpet’s tubing is approximately 1.5 meters long, find the wavelength of the standing wave.
  - Calculate the frequency of sound this standing wave produces, assuming the speed of sound is 343 m/s.
Doppler Effect
- The fastest bullet train in the world, the Shanghai Maglev, has a top velocity of approximately 128 meters per second.
 - If a constant, 440 Hz pitch were to be played from the train, find the frequency heard by someone seeing the train approaching them using the Doppler effect formula: $f' = f(\frac{v + vo}{v - vs})$ where $f'$ is the observed frequency, $f$ is the source frequency, $v$ is the speed of sound, $vo$ is the speed of the observer, and $vs$ is the speed of the source.
 - Draw a diagram demonstrating why the heard frequency is different from the real frequency.

UNIT 7-3: LIGHT

Reflection and Refraction
- Define reflection, refraction, and diffraction, and write 2-3 sentences explaining how each of these processes work.
  - Reflection: The bouncing back of light from a surface.
  - Refraction: The bending of light as it passes from one medium to another.
  - Diffraction: The spreading of waves around obstacles.
Laser Pointer and Glass Surface
- Consider a laser pointer that fires a red-colored beam onto a glass surface at a 50 degree angle.
  - Draw the direction of the reflected and refracted beam, labeling all known angles.
  - Discuss how the beam would change if the glass were made less dense.
Ray Diagrams
- An object is placed 20cm in front of a lens with a focal length of 10 cm.
  - Draw a ray diagram of how the light from the object travels to and through the lens.
  - Determine whether the image produced is a real or virtual image.
Reflecting Sphere
- An object is placed in front of a reflecting sphere. Draw a ray diagram of how the light from the object reflects off the mirror.
Light Rays and the Human Eye:
- Suppose you are looking at a school building. Draw a diagram of light rays traveling from the building and into your eyeball, including the lens.
Electromagnetic Spectrum Table:
- Complete the table below with the information provided.

UNIT 8: THERMODYNAMICS

Temperature and Heat Flow:
- Temperature is the measure of the average thermal energy in a substance, and heat tends to flow from higher temperatures to lower temperatures.
Temperature Conversions:
- Convert 40 degrees Celsius to Fahrenheit using the formula $F = \frac{9}{5}C + 32$ .
- Convert 200 degrees Fahrenheit to Celsius using the formula $C = \frac{5}{9}(F - 32)$ .
- Convert 300 Kelvin to degrees Celsius using the formula $C = K - 273.15$ .
- Convert -20 degrees Celsius to Kelvin using the formula $K = C + 273.15$ .
- Find a temperature such that the temperature in Fahrenheit is 100 times the temperature in Celsius by solving $F = 100C$ and $F = \frac{9}{5}C + 32$ simultaneously.
Heavy Water vs. Regular Water: