Units of Resistance: Ohms Explained with Examples

📚 Quick Study Guide

• 💡Resistance (R) is the opposition to the flow of electric current in a circuit.
• 📏 The unit of resistance is the ohm (Ω).
• Ohm's Law: $V = IR$, where V is voltage, I is current, and R is resistance.
• ⚡️Resistors are components designed to provide specific amounts of resistance.
• 🌡️Resistance can be affected by temperature; for most materials, resistance increases with temperature.
• ⚙️Series Resistance: Total resistance $R_{total} = R_1 + R_2 + R_3 + ...$
• 🔗Parallel Resistance: Total resistance $\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + ...$

🧪 Practice Quiz

1. What is the unit of electrical resistance?
1. (A) Volt
2. (B) Ampere
3. (C) Ohm
4. (D) Watt
2. Which formula correctly expresses Ohm's Law?
1. (A) $I = VR$
2. (B) $R = VI$
3. (C) $V = IR$
4. (D) $V = I/R$
3. If a circuit has a voltage of 12V and a current of 2A, what is the resistance?
1. (A) 4 Ω
2. (B) 6 Ω
3. (C) 10 Ω
4. (D) 24 Ω
4. What happens to the total resistance when resistors are connected in series?
1. (A) It decreases
2. (B) It increases
3. (C) It remains the same
4. (D) It becomes zero
5. What happens to the total resistance when resistors are connected in parallel?
1. (A) It increases
2. (B) It decreases
3. (C) It remains the same
4. (D) It doubles
6. A 10 Ω resistor and a 20 Ω resistor are connected in series. What is the total resistance?
1. (A) 10 Ω
2. (B) 20 Ω
3. (C) 30 Ω
4. (D) 2 Ω
7. A 12 Ω resistor and a 6 Ω resistor are connected in parallel. What is the total resistance?
1. (A) 18 Ω
2. (B) 9 Ω
3. (C) 4 Ω
4. (D) 2 Ω