Which of the following is NOT a form of energy?

• Kinetic

• Potential

• Elastic

• Colour

Answer explanation

Colour is not a form of energy; it is a characteristic of light. Kinetic, potential, and elastic are all types of energy associated with motion, position, and deformation, respectively.

Which of the following is an example of energy transformation?

• A light bulb turning electrical energy into light and heat

• A car parked on a hill

• Boiling water at a constant temperature

• A stretched rubber band

Answer explanation

A light bulb transforms electrical energy into light and heat, demonstrating energy transformation. The other options do not involve a change of energy form.

What does the Law of Conservation of Energy state?

• Energy is created and destroyed

• Energy can only be transferred through heat

• Energy can neither be created nor destroyed, only transformed

• Energy cannot change from one form to another

Answer explanation

The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another. This means the correct choice is that energy can neither be created nor destroyed, only transformed.

In a system where 100J of energy is supplied to a motor, only 80J is used to move the motor. What happens to the remaining 20J?

• It is destroyed

• It is lost as waste heat

• It is stored as potential energy

• It is used for light production

Answer explanation

The remaining 20J of energy is not destroyed but is lost as waste heat due to inefficiencies in the motor. This is a common occurrence in energy systems where not all supplied energy is converted into useful work.

A Sankey diagram shows energy input as 100J, and useful output as 60J. What is the percentage efficiency of the system?

• 40%

• 60%

• 75%

• 80%

Answer explanation

The efficiency of a system is calculated as (useful output / energy input) x 100. Here, (60J / 100J) x 100 = 60%. Therefore, the percentage efficiency of the system is 60%.

Which of the following strategies would reduce energy loss and increase the efficiency of a device?

• Increasing friction

• Insulating wires to reduce heat loss

• Adding more components to the circuit

• Allowing more energy to escape as heat

Answer explanation

Insulating wires reduces heat loss, which minimizes energy waste and enhances device efficiency. Increasing friction and allowing heat escape would lead to more energy loss, while adding components can complicate the circuit without improving efficiency.

Which of the following is an example of a renewable energy source?

• Coal

• Oil

• Geothermal

• Nuclear

Answer explanation

Geothermal energy is a renewable source derived from the Earth's internal heat, making it sustainable. In contrast, coal and oil are fossil fuels, and nuclear energy relies on finite uranium resources.

Which of the following is a common argument against using non-renewable energy sources?

• They are abundant and cheap

• They produce large amounts of greenhouse gases

• They are reliable and consistent

• They cause less environmental harm

Answer explanation

A common argument against non-renewable energy sources is that they produce large amounts of greenhouse gases, contributing to climate change and environmental degradation, making this the correct choice.

Which of the following statements about heat transfer is true?

• Convection occurs in solids

• Conduction transfers heat through direct contact

• Heat transfer through waves is called conduction

• Convection occurs in gases only

Answer explanation

Conduction is the process of heat transfer through direct contact between materials, making the statement 'Conduction transfers heat through direct contact' true. The other statements about convection and conduction are incorrect.

Which of the following is an example of convection?

• Boiling water

• A metal rod heating up

• A rock warming in the sun

• A light bulb emitting light

Answer explanation

Boiling water is an example of convection because the hot water rises and cooler water sinks, creating a circular motion. This process transfers heat through the fluid, unlike the other options which involve conduction or radiation.