11.5 Intensity

Quiz by John Farrant

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14 questions

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- Q1What is the correct definition of the intensity of a wave?Power passing through a surface per metre squaredEnergy transferred to a surface per unit areaPower passing through a surface per unit areaPower per unit area30s
- Q2What are the units of intensity?W m^2W m^-2Power per m^2J m^-230s
- Q3An astronaut is on the moon. He points a laser beam out into space. Will the intensity of the laser beam decrease with distance from the astronaut?No, because the waves from the laser are only in one direction and so don't spread out.Yes, because there are still a few particles in space that will absorb the energy.Yes, because, even though it is not a point source, the light waves will still spread out the further you get from a source.No, because space is a vacuum and so there are no particles to absorb the energy from the wave.30s
- Q4If you know the intensity of a wave on a surface, how can you work out the power of the wave?Divide the intensity by the surface's area.Multiply the intensity by the surface's area.Divide the intensity by the exposure timeMultiply the intensity by the exposure time30s
- Q5What is the relationship between intensity and distance for a wave that comes from a point source?Intensity (in W/m^2) is proportional to distance (in m^2)Intensity (in W/m^2) is proportional to distance (in m) squaredIntensity (in W/m^2) is inversely proportional to distance (in m^2)Intensity (in W/m^2) is inversely proportional to distance (in m) squared30s
- Q6Why does music sound louder the closer you get to a speaker?Because the waves have spread out lessBecause less energy has been lost at this point.Because there are less particles between you and the speakerBecause the waves have had less time to slow down30s
- Q7What happens to a wave that comes from a point source?The wave spreads out evenly in all directions.The energy stays concentrated in one point.The source is pointing in a certain direction.Only one wave is ever produced.30s
- Q8What is the equation to work out energy emitted using intensity?Intensity (in W/m^2) ÷ Area (in m^2) ÷ time (in s)Intensity (in W/m^2) x Area (in m^2) ÷ time (in s)Intensity (in W/m2) x Area (in m2) x time (in s)Intensity (in W/m^2) ÷ Area (in m^2) x time (in s)30s
- Q9What is the relationship between intensity and amplitude?Intensity is inversely proportional to amplitude squaredIntensity is proportional to amplitude squaredIntensity squared is proportional to amplitudeIntensity is directly proportional to amplitude30s
- Q10Is intensity always proportional to the square of the amplitude?No, only for tranverse waves.No, only for positive amplitudesNo, only for waves coming from a point source.Yes.30s
- Q11If the amplitude of wave halves what happens to the intensity of the wave?It doublesIt decreases by a factor of √2It quartersIt halves30s
- Q12If the intensity of a wave is doubled what happens to the amplitude of the wave?It increases by a factor of 4It increases by a factor of √2It increases by a factor of 2It decreases by a factor of √230s
- Q13The POWER of a wave that is 10m from its point source is 120W. What is the power of the wave at 20m?30W120W240W60W30s
- Q14The INTENSITY of a wave that is 10m from its point source is 120W m-2. What is the intensity of the wave at 20m?60 W m^-2240 W m^-2120 W m^-230 W m^-230s