High School Physics Exam Prep: Electric Fields and Circuits

📚 Quick Study Guide

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• Electric Field: The electric field $\vec{E}$ is the force per unit charge exerted on a test charge: $\vec{E} = \frac{\vec{F}}{q}$.
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• Electric Potential: The electric potential $V$ is the electric potential energy per unit charge: $V = \frac{U}{q}$. The potential difference between two points is $\Delta V = -\int \vec{E} \cdot d\vec{l}$.
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• Capacitance: Capacitance $C$ is the ratio of charge $Q$ stored on a capacitor to the potential difference $V$ across it: $C = \frac{Q}{V}$. For a parallel-plate capacitor: $C = \frac{\epsilon_0 A}{d}$, where $\epsilon_0$ is the permittivity of free space, $A$ is the area of the plates, and $d$ is the separation between the plates.
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• Current: Current $I$ is the rate of flow of charge: $I = \frac{\Delta Q}{\Delta t}$.
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• Resistance: Resistance $R$ is the opposition to the flow of current: $R = \frac{V}{I}$ (Ohm's Law).
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• Power: Electric power $P$ is the rate at which electrical energy is converted to other forms of energy: $P = IV = I^2R = \frac{V^2}{R}$.
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• Series Circuits: Resistors in series have the same current flowing through them. The total resistance is $R_{eq} = R_1 + R_2 + R_3 + ...$.
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• Parallel Circuits: Resistors in parallel have the same voltage across them. The reciprocal of the total resistance is $\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + ...$.

🧪 Practice Quiz

1. What is the electric field strength at a point where a $5 \mu C$ charge experiences a force of $0.01 N$?
1. A) $200 N/C$
2. B) $2000 N/C$
3. C) $5000 N/C$
4. D) $50 N/C$
2. A parallel-plate capacitor has a capacitance of $10 \mu F$. If the charge on the capacitor is $20 \mu C$, what is the voltage across it?
1. A) $0.5 V$
2. B) $2 V$
3. C) $200 V$
4. D) $30 V$
3. A wire carries a current of $2 A$. How much charge passes through a cross-section of the wire in $5$ seconds?
1. A) $2.5 C$
2. B) $10 C$
3. C) $0.4 C$
4. D) $7 C$
4. A $10 \Omega$ resistor has a voltage of $5 V$ across it. What is the current flowing through the resistor?
1. A) $0.5 A$
2. B) $2 A$
3. C) $50 A$
4. D) $15 A$
5. What is the equivalent resistance of two $6 \Omega$ resistors connected in parallel?
1. A) $12 \Omega$
2. B) $3 \Omega$
3. C) $6 \Omega$
4. D) $0 \Omega$
6. A lightbulb is rated at $60 W$ and operates at $120 V$. What is the current flowing through it?
1. A) $0.5 A$
2. B) $2 A$
3. C) $7200 A$
4. D) $0.2 A$
7. Which of the following statements is true about resistors connected in series?
1. A) The voltage across each resistor is the same.
2. B) The current through each resistor is the same.
3. C) The equivalent resistance is less than the smallest resistance.
4. D) The power dissipated in each resistor is the same.