Answer:
A. K = 0.546 eV
B. cooper and iron will not emit electrons
Explanation:
A. This is a problem about photoelectric effect. Then you have the following equation:
(1)
K: kinetic energy of the ejected electron
Ф: Work function of the metal = 2.48eV
h: Planck constant = 4.136*10^{-15} eV.s
λ: wavelength of light = 410nm - 750nm
c: speed of light = 3*10^8 m/s
As you can see in the equation (1), higher the wavelength, lower the kinetic energy. Then, the maximum kinetic energy is obtained with the lower wavelength (410nm). Thus, you replace the values of all variables :
B. First you calculate the energy of the photon with wavelengths of 410nm and 750nm
You compare the energies E1 and E2 with the work functions of the metals and you can conclude:
sodium = 2.3eV < E1
cesium = 2.1 eV < E1
cooper = 4.7eV > E1 (this metal will not emit electrons)
iron = 4.5eV > E1 (this metal will not emit electrons)
Answer:
a) The trajectory will be a helical path.
b) θ = 2*π rad
Explanation:
a) Since the initial velocity of the particle has a component parallel (x-component) to the magnetic field B
, the trajectory will be a helical path.
b) Given
t = 2*π*m/(q*B)
We can use the equation
θ = ω*Δt
where
θ is the angular displacement
ω is the angular speed, which is obtained as follows:
ω = q*B/m
then we have
θ = (q*B/m)*2*π*m/(q*B)
⇒ θ = 2*π rad
Answer:
Will be doubled.
Explanation:
For a capacitor of parallel plates of area A, separated by a distance d, such that the charges in the plates are Q and -Q, the capacitance is written as:
where e₀ is a constant, the electric permittivity.
Now we can isolate V, the potential difference between the plates as:
Now, notice that the separation between the plates is in the numerator.
Thus, if we double the distance we will get a new potential difference V', such that:
So, if we double the distance between the plates, the potential difference will also be doubled.
Answer:
vertical force cannot change the velocity on the x-axis. t =x/v₀ₓ
Explanation:
The force is a vector magnitude, so the forces on the x-axis affect the acceleration on this axis. Consequently a vertical force cannot change the velocity on the x-axis.
= m g
Fₓ = 0
The horizontal velocity in projectile motion is constant, if we neglect the air resistance, so it can be used to find the time of a horizontal displacement
x = v₀ₓ t
t =x/v₀ₓ
The only magnitude that is the same for both movements is the time that is a scalar
The dependent variable was the time and the independent variable was thecars
