The Joule is the SI unit for measuring energy. Other units such as Watt measure power and do not directly indicate energy.

Electrical power is measured in watts, which represents the rate at which energy is consumed or transformed. Joules are used to measure energy, not the rate of its usage.

Batteries store energy in the form of chemical energy, which is released as electrical energy when the battery is used. The other options describe different forms of energy not typically stored in a battery.

Energy conversion is the process of transforming energy from one form to another. It adheres to the law of conservation of energy, meaning energy is neither created nor destroyed during the process.

The law of conservation of energy states that energy in a closed system remains constant and cannot be created or destroyed. It simply changes from one form to another, ensuring that the total energy is conserved.

Electrical energy is determined by multiplying power by the time over which the power is used. This relationship illustrates how longer operating times result in greater energy consumption.

Since 1 hour equals 3600 seconds, 2 hours is 7200 seconds. Multiplying 100 watts by 7200 seconds results in 720,000 Joules of energy consumed. This problem reinforces the relationship between power, time, and energy.

Kinetic energy is the energy an object possesses due to its motion, largely influenced by its mass and speed. The other options refer to chemical, potential, or thermal forms of energy, which are distinct from kinetic energy.

In a light bulb, electrical energy is converted into both light and heat energy. This dual conversion highlights the practical application of energy transformation in everyday devices.

The ampere, often shortened to 'amp,' is the SI base unit for electrical current. Understanding this unit is fundamental for analyzing any electrical circuit.

Improving energy efficiency involves minimizing energy losses that can occur during conversion and transmission. This approach ensures more effective use of the available energy.

A generator is designed to convert kinetic (mechanical) energy into electrical energy, typically through electromagnetic induction. In contrast, batteries store energy rather than converting mechanical energy.

A transformer is used to modify AC voltage levels either by stepping them up or stepping them down. It plays a crucial role in efficient power transmission over long distances.

Work is calculated as the product of force and displacement in the direction of the force. Knowing the displacement is essential to determine how much energy is transferred.

Renewable energy comes from sources like sunlight, wind, and water that naturally replenish over time. This sustainability is a key differentiator from non-renewable sources such as fossil fuels.

At 20% efficiency, the panel produces 20% of 5000 J, which is 1000 J of electrical energy. This question demonstrates the practical impact of efficiency in energy conversion.

Energy losses in circuits commonly occur as heat, a result of electrical resistance in the components. Recognizing these losses helps in designing more efficient electrical systems.

Water stored at a height possesses gravitational potential energy, which is converted into kinetic energy as it falls, and then into electrical energy. This sequence is fundamental to the operation of hydroelectric plants.

With an efficiency of 85%, the motor outputs 85% of 2000 J, which equals 1700 J of mechanical energy. This problem emphasizes how efficiency affects the actual energy output in devices.

The work done is calculated as m × g × h = 50 × 9.8 × 3 = 1470 J. Dividing this work by 4 seconds gives an average power of 367.5 W, which demonstrates the calculation of power from work and time.