A) We want to find the work function of the potassium. Apply this equation:
E = 1243/λ - Φ
E = energy of photoelectron, λ = incoming light wavelength, Φ = potassium work function
Given values:
E = 2.93eV, λ = 240nm
Plug in and solve for Φ:
2.93 = 1243/240 - Φ
Φ = 2.25eV
B) We want to find the threshold wavelength, i.e. find the wavelength such that the energy E of the photoelectrons is 0eV. Plug in E = 0eV and Φ = 2.25eV and solve for the threshold wavelength λ:
E = 1243/λ - Φ
0 = 1243/λ - Φ
0 = 1243/λ - 2.25
λ = 552nm
C) We want to find the frequency associated with the threshold wavelength. Apply this equation:
c = fλ
c = speed of light in a vacuum, f = frequency, λ = wavelength
Given values:
c = 3×10⁸m/s, λ = 5.52×10⁻⁷m
Plug in and solve for f:
3×10⁸ = f(5.52×10⁻⁷)
f = 5.43×10¹⁴Hz
Answer:
0.050 m
Explanation:
The strength of the magnetic field produced by a current-carrying wire is given by

where
is the vacuum permeability
I is the current in the wire
r is the distance from the wire
And the magnetic field around the wire forms concentric circles, and it is tangential to the circles.
In this problem, we have:
(current in the wire)
(strength of magnetic field)
Solving for r, we find the distance from the wire:

Answer:
30.36°
Explanation:
By using linear momentum; linear momentum can be expressed by the relation:

where ;
m= mass
= velocity of components in the x direction
= velocity of components in the y direction
If we consider the east as the positive x and north as positive y which is synonymous to what we usually have on a graph.
Then;
Initial momentum = 
= 
However, the masses stick together after collision and move with a common velocity: 
∴ Final momentum = 
= 
From the foregoing ;
initial momentum = final momentum

So;



Finally;
The required angle θ = 
θ = 
θ = 
θ = 30.36°
Answer:
I think its B. Please keep in mind that I could be wrong.
Explanation: