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Explain how the photoelectric effect gives evidence for the photon theory of light.

When light is shone onto a piece of metal, if the light is below a certain frequency, no photoelectrons are emitted. Only if the light is above a certain frequency, known as the threshold frequency, are phot...
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Answered by Tamanna D. • Physics tutor
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State Ohm's Law and the main characteristics of ohmic conductors, giving examples

Ohm's law states V=R×I, which means that the voltage difference V across a component and the current I flowing across it are directly proportional one another, and the proportionality coefficient is the resi...
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The teacher quickly inverts the can containing boiling water into a bowl of cold water, as shown in the diagram. When the can is inverted in the cold water, the can collapses. Use ideas about particles and pressure to explain why the can collapses.

Initially the average kinetic energy of the trapped air within the can is much higher the surrounding body of air. However, when immersed in the cold water, there is a significant decrease in the average kin...
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Answered by Zubin M. • Physics tutor
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State what is meant by resonance and provide some examples where it is crucial.

Resonance is where a system is forced to oscillate at a frequency close or at its natural frequency. The result of the forced oscillation produces a maximum energy transfer and, therefore, a large increase i...
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Answered by Zubin M. • Physics tutor
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A particle of mass 5kg is acted upon by a force of 400N for a distance of 20m along the x axis. What is its final velocity if it is initally at rest?

The work done by a force on a particle is: Work done = Force x Displacement.The energy of a particle is given by the sum of its potential and kinetic energies.As the particle does not gain or lose any height...
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Answered by Luke T. • Physics tutor
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