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Photoelectrons with a maximum speed of 7.00 Β· 105 m/s are ejected from a surface in the presence of light with a frequency of 8.00 Β· 1014Hz. If the mass of an electron is 9.1 Β· 10-31 kg, calculate the maximum kinetic energy of a single electron, in joules.

_____ J


6.3 x 10-25
4.4 x 10-19
3.2 x 10-25
2.2 x 10-19

Respuesta :

This is just testing your ability to recall that kinetic energy is given by:Β 

k.e. = Β½mvΒ²Β 

where m is the mass and v is the velocity of the particle.Β 

The frequency of the light is redundant information.Β 

Here, you are given m = 9.1 * 10^-31 kg and v = 7.00 * 10^5 m/s.Β 
Just plug in the values:Β 

k.e. = Β½ * 9.1 * 10^-31 * (7.00 * 10^5)Β²Β 
k.e. = 2.23 * 10^-19 JΒ 
so it will be d:2.2*10^-19 J

Answer:

2.23 Γ— 10 -17 J

Explanation:

The question may have been put in wrong, I have 7.00 * 10^6, which gives you the answer above instead.

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