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- 1. Ohm’s Law When its dark, you just press turn on the light switch. It is quiet interesting to know how the room gets lighted in a blink of an eye.
- 2. When electricity flows through the circuit, it experiences hindrance. This hindrance is also known as the resistance. In a circuit, the wires and connections have internal resistances that hinder (resist) the flow of charges. If the circuit is not complete, there will be no current flowing through it. Ohm’s Law states that voltage is directly proportional to current under constant resistance.
- 3. Mathematically, this is written as: V = IR Where V = Voltage in V I = current in A R = resistance in Ω Consider the following sample problems to apply the formula of Ohm’s law.
- 4. Example: What is the voltage of a circuit if the current passing through it is 1.50 A and the total resistance is 23 Ω? Solution: I = 1.50 A R = 23 Ω V = ? V = IR V = (1.50 A) (23 Ω) V = 34.5 V So, the voltage of the circuit is 34.5 V.
- 5. Georg Simon Ohm formulated Ohm’s law. He found the relationship among voltage, resistance and current and expressed it as V = IR. Most materials follow Ohm’s law, but there are few materials that do not abide by this law. These are called non-ohmic materials.
- 6. VOLTAGE 7 Voltage, which is also known as electromotive force or potential difference is the electric pressure that causes current to flow. The voltage level is similar to the pressure of water at different heights.
- 7. VOLTAGE 8 The symbol for voltage is V.
- 8. RESISTANCE 9 Resistance is the opposition a material offers to current. The symbol for resistance is R.
- 9. RESISTANCE 10 All materials offer some resistance to current, but the amount of resistance differs from each other. There are high-resistance and low-resistance materials. More energy is required to move electrons through high- resistance materials.
- 10. ELECTRICITY 11
- 11. Problem-Solving: 12 1.) How much current flows through a lamp with resistance 90 Ω when it is connected to a 220-V outlet?
- 12. Problem-Solving: 13 2.) How much current flows through a lamp with resistance 50 Ω when it is connected to a 300-V outlet?
- 13. Problem-Solving: 14 3.) How much current flows through a lamp with resistance 36 Ω when it is connected to a 720-V outlet?
- 14. Problem-Solving: 15 4.) How much current flows through a lamp with resistance 45 Ω when it is connected to a 2756-V outlet?
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- 18. SAFETY WITH CIRCUIT 19 • Circuit breaker - is like an automatic switch that turns of the circuit when there is overloading of current (which can cause fire). • Fuse - This is sometimes referred to as the sacrificial device. This is because fuse melts when there is overloading of current. This prevents damage to the circuit.
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- 21. Performance Task Direction: You and your classmates are tasked to decorate your classroom using Christmas lights. After that discuss how Ohm’s law works with your performance task. Your output will be evaluated using the following criteria's, creativity 10 points, uniqueness 10 points, class participation 10 points.