Engineers who design battery-operated devices such as cell phones and mp3 players try to make them as efficient as possible. an engineer tests a cell phone and finds that the batteries supply 10,000 j of energy to make 5500 j of output energy in the form of sound and light for the screen. how efficient is the phone?

efficiency= [useful energy transferred ÷ total energy supply]×100%

So, [5500÷10000]×100%=0.55×100

                                        =55%

no. bullets are macro objects. wave nature is for light waves, extremely tiny particles. if a light particle was the size of your finger, the bullet would be the size of the universe. so basically, that huge difference in size makes the wave nature of matter insignificant.