The wavelength of a certain laser is 445 nm, and the power of the laser is 2.30

Question

The wavelength of a certain laser is 445 nm, and the power of the laser is 2.30 W. How many photons are released if the laser is used for 0.11 second.

Question 4 options:

1.126e+002

4.699e+007

5.660e+017

2.237e+018

I did 2.30 x 0.11/6.63e-34 x 6.74e14 = my anser was 4.09e18 but thats not an option

A metallic surface is illuminated with light of wavelength 461 nm. If the work function for this metal is 1.60 eV, what is the kinetic energy of the ejected electrons?

Question 5 options:

1.30 eV

1.09 eV

4.29 eV

1.60 eV

2.69 eV

I did 6.626E-34 x 3.0E8/ 461E-9 - 1.60(1.6E-19) and got the wrong anwer

What is the wavelength of an electron moving with a speed of 1210 m/s? The mass of an electron is 9.109e-31 kg.

Question 2 options:

1203 nm

401 nm

602 nm

301 nm

1.126e+002

4.699e+007

5.660e+017

2.237e+018

I did 2.30 x 0.11/6.63e-34 x 6.74e14 = my anser was 4.09e18 but thats not an option

A metallic surface is illuminated with light of wavelength 461 nm. If the work function for this metal is 1.60 eV, what is the kinetic energy of the ejected electrons?

Question 5 options:

1.30 eV

1.09 eV

4.29 eV

1.60 eV

2.69 eV

I did 6.626E-34 x 3.0E8/ 461E-9 - 1.60(1.6E-19) and got the wrong anwer

What is the wavelength of an electron moving with a speed of 1210 m/s? The mass of an electron is 9.109e-31 kg.

Question 2 options:

1203 nm

401 nm

602 nm

301 nm

Explanation / Answer

a)

f =c/lambda =3*10^8/445*10^-9=6.74*10^14 Hz

n= pt/hf =2.3*0.11/(6.63*10^-34)*(6.74*10^14)

n=5.66*10^17

so C is correct

b)

KE =(hc/lambda)-phi

KE =(6.63*10^-34)*(3*10^8)/(461*10^-9) -1.6*(1.6*10^-19)

KE=1.75*10^-19 J

KE =1.75*10^-19/1.6*10^-19

KE=1.09 eV

c)

lambda =h/mV =(6.63*10^-34)/(9.109*10^-31)*(1210)

lambda =602 nm

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