What is the main energy transformation in a cooker?
Electrical to sound energy
Electrical to heat energy
Electrical to light energy
What is the main energy transformation in a toaster?
Which of the following is the correct equation for calculating electrical power?
\[\text{Power} = \text{energy} \times \text{time}\]
\[\text{Power} = \text{time} \div \text{energy}\]
\[\text{Power} = \text{energy} \div \text{time}\]
What power rating should a kettle that uses \(20\, 000\, J\) of energy in 10 seconds have?
\[0.0005\, W\]
\[2000\, W\]
\[200\,000\, W\]
What is the typical power rating of a hair-dryer?
\[135\, W\]
\[1200\, W\]
\[9000\, W\]
What is the typical power rating of a fridge?
\[1000\, W\]
What happens to energy during energy transformations?
Energy is made from nothing
Energy cannot be made or destroyed, it can only be transformed from one type to another
Energy is destroyed and lost forever
In what form is energy generally lost to the surroundings?
Heat or sound
Electricity
Kinetic
How do we calculate efficiency?
\[\text{Efficiency} = (\frac{{useful\,output}}{{input}}) \times 100\]
\[\text{Efficiency} = (\frac{{input}}{{useful\,output}}) \times 100\]
\[\text{Efficiency} = \left( {\frac{{useful\,output}}{{input}}} \right) \div 100\]
What is the percentage efficiency of an electric drill that uses \(300\, J\) of electrical energy each second but only does \(100\, J\) of useful work?
\[0.33\%\]
\[300\%\]
\[33\%\]