Energy & Efficiency Revision

Which of the following is not an energy store?

• kinetic

• elastic

• electrical

• thermal

Which of the following are energy stores?

• mechanical

• nuclear

• radiation

• magnetic

Which appliance is designed to transfer electrical energy to thermal energy?

• A - food mixer

• B - kettle

• C - lamp

• D - radio

Which appliance is designed to transfer electrical energy to kinetic energy?

• A - food mixer

• B - kettle

• C- lamp

• D - radio

Before the student jumps from the bridge he has a store of ______________ energy.

When he is falling, the student's store of ______________

energy increases.

When the bungee cord is stretched, the cord stores energy as ______________ energy.

• gravity, kinetic, elastic

• elastic, kinetic, gravitational

• gravitational, kinetic, elastic

• gravitational, movement, stretching

Which is the correct equation for calculating efficiency?

• efficiency =(useful energy output)/(total energy input)×100%

• efficiency =(useful energy input)/(total energy output)×100%

• efficiency =(total energy output)/(useful energy input)×100%

• efficiency =(waste energy output)/(total energy input)×100%

A fluorescent lamp is 25% efficient. Choose the statement that correctly describes how the lamp performs.

• the lamp only works for quarter of the time.

• 25% of the electrical energy transferred to the lamp is wasted

• the lamp does not work properly

• 25% of the energy supplied to the lamp is transferred to light

An electric motor is used to raise an object. The object's gravitational potential energy store increases by 60J when the motor is supplied with 200J of energy by an electric current. Calculate the percentage efficiency of the motor.

Calculate the efficiency of the TV.

• 60%

• 56%

• 4%

• 39%

A power station needs an input of 188 J each second to operate a single 60 W lamp in a house. The Sankey diagram shows what happens to the input energy at each stage. Calculate the overall efficiency from power station input to lamp.

• 2.6 %

• 0.80 %

• 2.5 %

• 0.0080 %