Physics Alevel: Particles and Quantum Phenomena Part 2 (savemyexams)

Photoelectric effect, Energy levels and Photon emission

Define an electronvolt?

The energy gained by an electron travelling through a potential difference of one volt.

What is the the equation from which the electronvolt is derived from?

potential difference: V= E/Q

What is the value of 1 eV in joules?

1 eV = 1.6 x 10^-19 J

How do you convert MeV to J?

1\.6x10^-19 x 1x10^6

When a charged particle is accelerated through a potential difference what does it gain?

kinetic energy

Finish the gaps:

If an ____ accelerates from __----__ __*,*__ an electronvolt is __----__ to the kinetic energy ----------.

1) electron

2) rest

3) equal

4) gained

If eV is = to the kinetic energy what is the equation?

eV = 1/2mv^2

Give the equation for the speed of the electron?

v= √2eV/m

How to convert from nano units to standard units?

x10^-9

What is the wave speed equation and the units?

c = fλ

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units:

c: ms^-1

f: Hz

λ: m

1. What is formula for photon energy? and what is h?
2. and substituting the wave speed equation

1) E = hf

E is energy in J

h is planck’s constant

2) E = hc/λ

What is the photoelectric effect? and define it?

The phenomena in which Photoelectrons are emitted from the surface of a metal upon the absorption of light above a certain frequency.

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Photons of sufficient energy are able to free electrons from the surface of a metal.

What are electrons removed from a metal through the photoelectric effect called?

photoelectrons

Define the threshold frequency?

The minimum frequency of incident electromagnetic radiation required to remove a photoelectron from the surface of a metal

Define the threshold wavelength?

The longest wavelength of incident electromagnetic radiation that would remove a photoelctron from the surface

How are the threshold wavelength and frequency related? and what does c represent in this situation?

c = fλ

c is the speed of light since photons are particles of light.

What is the value for the speed of light?

3\.00 x 10^8

What is the value for plancks constant?

6\.63 x 10^-34