In a photoelectric-effect experiment it is observed that no current flows unless the wavelength is less than 570 nm .
a) what is the work function of this material?
b) what is the stopping voltage required if light of wavelength 420 nm is used?

0.77842 V

Explanation:

h = Planck's constant =

c = Speed of light =

= Wavelength

Work function is given by

The work function is

Stopping voltage is given by

The stopping voltage required is 0.77842 V

(a) 3.49 x 10^-19 J

(b) 0.78 V

Explanation:

threshold wavelength, λo = 570 nm = 570 x 10^-9 m

(A) the work function of the metal is given by

where h is the Plank's constant and c be the speed of light.

h = 6.63 x 10^-34 Js

c = 3 x 10^8 m/s

Ф = 3.49 x 10^-19 J

(B) λ = 420 nm = 420 x 10^-9 m

Use Einstein relation

where, Vo is the stopping potential

eVo = 1.246 x 10^-19

Vo = 0.78 V

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

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the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.