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Why can heat only be transferred through a vacuum by radiation, and not conduction or convection? (3)

Heat transfer by conduction and convection works by particles colliding and transferring energy, as there are no particles in a vacuum heat transfer can only occur by radiation. This is because radiation inv...
JW
Answered by James W. • Physics tutor
43540 Views

Explain the photoelectric effect, when does it occur and what is its significance in understanding the nature of light ? (6)

metal (unlike insulators ) contains free electrons (1) kinetic energy transferred from the light incident on the surface to the free electrons (1) The maximum kinetic energy of the electrons depends on the f...
HR
Answered by Helena R. • Physics tutor
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The mercury atoms in a fluorescent tube are excited and then emit photons in the ultraviolet region of the elecrtomagnetic spectrum. Explain how the mercury atoms become excited.

The mercury atom is excited one of its electrons goes from an upper electron shell to a lower electron shell thanks to some energy that it recives from the outside. When an atom is excited it is instable so ...
MB
Answered by Marie B. • Physics tutor
5650 Views

In the Photoelectric effect, Why does increasing the light intensity have no effect on the energy of the electron emitted?

The equation to calculate the energy of an emitted electron is: E = hf - φ , where E is the energy of the electron emitted, h is the Planck's constant, f is the frequency of the light and φ is the work funct...
PK
Answered by Pankaj K. • Physics tutor
24642 Views

why is gravitational potential negative?

the gravitational potential is set to be 0 at a distance of infinity.
NS
Answered by Navdeep S. • Physics tutor
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