Current Electricity Study Notes

Current Electricity Practice Test

Handy Ideas

Formulas:
- Voltage ( ext{AV}) = Current ( ext{I}) × Resistance ( ext{R})
- Voltage Difference: J2 - J1
- m = \frac{X2 - X1}

Modified True/False - 8 marks

Series Circuit Rules:
- Total Resistance, R = R₁ + R₂ + R₃ + …
- Total Voltage ( ext{AV}) = ext{AV₁} + ext{AV₂} + ext{AV₃}…
Parallel Circuit Rules:
- Total Voltage ( ext{AV}) = ext{IR}
- Current ( ext{I}) = ½ + ½ + …
- Total Voltage ( ext{AV}) = ext{AV₁} = ext{AV₂} = ext{AV₃}…

True or False Statements

False: Parallel circuits have one path for current.
- Correction: Parallel circuits have multiple paths.
False: As voltage increases, so does resistance.
- Correction: The current also goes up when voltage increases.
False: More resistance leads to more current if voltage is constant.
- Correction: More resistance = less current.
True: Current in a series circuit is constant.
False: Total voltage rise of a battery in parallel circuits is the sum of the voltage drops.
- Correction: Voltage rise in parallel circuits stays the same.
True: As voltage increases in a series circuit, so does the brightness of a light.
True: Slope of a voltage and current graph is equal to the resistance in a series circuit.
True: A continuous path for electron flow is called an electric circuit.

Multiple Choice - 5 marks

What is the name of a type of circuit in which an electrical load (resistor) may be disconnected without affecting other loads?
- b) Parallel circuit
Two identical bulbs x and y are connected in series to a power source. If the circuit is turned on and bulb x is unscrewed, the brightness of bulb y will:
- d) Become zero (no light)
For any electrical device to operate, there must be a flow of:
- c) Electrons
What is the definition of current (I), and its unit of measurement?
- d) The rate of flow of electric charge, measured in Amperes (A).
What is the measure of the energy provided to charge, or the difference in electric energy per unit charge between two points in a circuit?
- c) Voltage

Short Answer:

A battery, bulb, and wires are connected.
- a) Explain: Is the circuit open or closed or a short circuit?
  - Answer: It is an open circuit because the wires/connectors are not connected to the metal part of the bulb.
- b) Explain: Will the bulb light up? Justify your answer.
  - Answer: No, because it's not connected to the metal input. Grass is an insulator.
Is the following circuit series or parallel? Explain the reason for your answer.
- Answer: It is a parallel circuit because there is more than one pathway for the electrons to flow through.
An automobile headlight has an average resistance of 24.0 . Car batteries provide a potential difference of 12.0 V. What amount of current passes through the headlight?
- Steps:
  - Describe the math: Use the voltage equation to solve for I.
  - Write the equation:
    $I = \frac{V}{R}$
  - Substitute values with units:
    $I = \frac{12.0 V}{24.0 \, \Omega}$
  - Calculate:
    $I = 0.5 A$
  - State conclusion: The total current passing through the headlight is 0.5 A.
Data was measured for a certain resistor and graphed.
- Determine the slope of the line in the graph above.
- Steps:
  - Describe the math: Find the slope of the line.
  - Write the equation:
    $M = \frac{\Delta V}{\Delta I}$
  - Isolate the unknown: Find the rise over run.
  - Substitute values with units: Use data points to calculate.
  - Calculate:
  - State conclusion: The slope of the line is 3.
- Explain how the slope of the line would change if a stronger resistor was used.
  - Answer: The slope would be steeper if there were a stronger resistance.
- What is the resistance of the resistor that generated the data on the graph above?
  - Answer: The resistance is 3 .
Draw a circuit diagram based on the image above using the correct circuit symbols.
- Label the junction points in the circuit diagram above.
Calculate: Bulb A has IA = 0.61 A and a voltage of AVA = 6.98 V; Bulb B has IB = 12 A of current flowing through it. The total resistance of the circuit Rs = 0.95 . Calculate the total current (Is) and total voltage (AVS) in the circuit.
- Math Work
  - Total Current:
    $I<em>s = I</em>A + I_B = 0.61 A + 12 A = 12.61 A$
  - The total current is 12.61 A.
  - Total Voltage:
    $V<em>s = I</em>s imes R_s = 12.61 A \times 0.95 \Omega = 11.98 V$
  - The total voltage is 11.98 V.

Electricity Learning Log

Name: Colton M.
As a young scientist, you will be conducting experiments to explore how electricity works. You need to keep track of the new ideas and skills that you learn!

Skill and Idea Descriptions:

Describe each skill or idea using just a few words (10 words or less).
Draw a simple picture or example to represent each skill or idea.

Electricity Concepts:

Electricity 1: A Mysterious Interaction
- Idea: Charging - Tiny pieces of charged matter move from one object to another.
- Interaction: Objects can attract or repel each other.
- Static Electric Interaction: Objects can gain charge.
- Discharging: Removing extra charge from an object.
Electricity 2: Exploring Electric Charge
- Positive and Negative Charge: Charges transfer between objects.
Electricity 3: Charges in Solid Matter
- Neutral: Equal number of positive and negative charges.
- Electrons: Particles with negative charges.
- Charge Diagrams: Diagrams illustrate charge distribution on objects.
Electricity 4: Conductors and Insulators
- Charging by Friction: Transfer of electrons when objects are rubbed.
- Insulators: Materials that do not allow electrons to move easily.
- Charging by contact (Conduction): Contact transfers electrons.
- Conductors: Materials that facilitate electron flow.
- Grounding: Connecting to a larger body to remove charge.
Electricity 5: Polarization of Insulators
- Polarization: Process where electrons separate within insulators.
- Electrons not mobile in insulators.
- Skill: Drawing Polarized Charts.
Electricity 6: Polarization of Conductors
- Mobile Electrons: Electrons that move freely in conductors.
Electricity 7: Electron Current
- Electron Current: Movement of electrons constitutes current.
- Source: Electrons flow from a source of current.
Electricity 8: Electric Circuits and Current
- Open Circuit: Circuit is disconnected.
- Closed Circuit: Circuit is connected.
- Short Circuit: Electrons bypass components.
- Skill: Circuit Diagram.
Electricity 9: Current Flow and Loads
- Conservation of Charge: Charges are not lost in current flow.
- Energy: The capacity to perform work in a circuit.
- Rope Model for Current: Visualizing electric circuit flow.
Electricity 10: Electric Energy
- Skill: Measuring Voltage.
- Voltage measures energy change of electrons moving between points.
Electricity 11: Voltage, Current, and Resistance
- Resistance: Measured in ohms; opposition to current flow.
Electricity 12: Ohm's Law
- Ohm's Law: Current (I) in a circuit is defined as:
  $I = \frac{V}{R}$
Electricity 13: Circuit Connections - Series
- Series Connection: Components connected in a single path.
- Current is constant in series circuits.
Electricity 14: Circuit Connections - Parallel
- Junction: Circuit point where current splits.
- Loads in Parallel Rule: Total current increases with parallel loads.

Electricity Test #2 Evaluation Page

Evaluate understanding of charge transfers and circuit drawings.
Grading Criteria: Different aspects are rated to measure proficiency on concepts.