Energy Transfers and Stores (Energy 1)

Geothermal energy harnesses the heat generated within the Earth, often from radioactive decay, to produce steam and generate electricity.

Solar energy systems use photovoltaic cells or mirrors to convert sunlight directly into electricity or heat.

Non-renewable resources exist in finite amounts and cannot be replenished on a human timescale, meaning they will eventually run out.

Useful energy = total energy input * efficiency. 1000 J * 0.55 = 550 J.

Efficiency = useful power output / total power input. 900 W / 1200 W = 0.75.

Efficiency is defined as the ratio of useful energy or power output to the total energy or power input.

According to the law of conservation of energy, energy cannot be created. Some energy is always dissipated as waste, so output can never exceed input.

Power = energy / time. Energy = 4800 J, time = 120 seconds. 4800 / 120 = 40 W.

Convection involves the movement of warmer, less dense fluid rising and cooler, denser fluid sinking, creating a current. It is not about particles moving toward hotter regions.

Conduction is the primary method of heat transfer in solids, where kinetic energy is passed from vibrating particle to vibrating particle through collisions.

A vacuum flask is designed to minimize heat transfer through conduction, convection, and radiation. By creating a vacuum, it prevents heat from escaping or entering the container.

When thermal energy transfers to the surroundings, the object loses heat, causing its temperature to decrease rather than increase. Heating up occurs when an object absorbs thermal energy.

The principle stating that energy cannot be created or destroyed, only transformed from one form to another, is the Law of Conservation of Energy.

An electrical fan converts electrical energy into mechanical energy, which manifests as the kinetic energy of the spinning blades.

A standard lightbulb requires an electrical current to function, making electrical energy the input.