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Electric power is an essential concept in understanding how electrical systems work. It is defined as the rate at which electrical energy is converted into another form, such as heat, light, or motion, through a device such as a resistor.The formula to calculate electric power is given by:

• \( P = \frac{V^2}{R} \)
• \( P = V \cdot I \)

Here, \( P \) stands for power in watts (W), \( V \) is the voltage in volts (V), \( I \) is the current in amperes (A), and \( R \) is resistance in ohms (\( \Omega \)).Using the formula \( P = \frac{V^2}{R} \), we calculate power when only voltage and resistance values are known. The formula \( P = V \cdot I \) is used when both voltage and current are given. Understanding how to interchangeably use these formulas can help you solve a variety of power-related problems in electronics. The unit of power, the watt, signifies how much energy the device is using per second. The higher the power rating, the more efficient the device is at converting electrical energy into work. In this context, a heater converts electrical energy primarily into heat.

Resistance is a measure of how much an object opposes the passage of an electric current. When dealing with resistors, it's crucial to understand that they convert electrical energy into heat, thereby affecting the overall power output of an electrical appliance.The resistance of an object is measured in ohms (\( \Omega \)) and can be impacted by various factors, like:

• The material of the resistor
• Its temperature
• The physical dimensions of the resistor

In a simple resistor circuit, Ohm's Law, which is \( V = I \cdot R \), relates voltage \( V \), current \( I \), and resistance \( R \). This fundamental principle allows us to calculate one of these quantities if the other two are known. For example, knowing the resistance and current allows you to determine the voltage.In our exercise, the electric heater has a resistance of \(25 \Omega\). This determines how much current will flow through the heater when connected to a voltage source, impacting how much electric power is dissipated as heat.

Voltage, often referred to as electric potential difference, is a measure of the energy difference per charge between two points in an electrical circuit. It's essentially the "push" that makes electric charges move in a wire, driving the current through a circuit.Measured in volts (V), voltage can be thought of as the force that causes electrons to flow through a conductor. In a practical sense, increasing the voltage increases the power output of an electrical device if resistance stays the same (as shown by \( P = \frac{V^2}{R} \)).There are some key points to remember about voltage:

• It is measured across components, such as a battery or resistor.
• Higher voltage means more potential energy is available.
• In the context of alternating current (AC) supply, it is often the root mean square (RMS) value that is used.

In the exercise, the heater is connected to a \(120 \mathrm{V}\) outlet, which provides the necessary electric pressure to drive the current through the heater's resistance, converting electrical energy into heat. Understanding voltage helps in grasping how various electrical components interact within a circuit.