Convection currents<span> are </span>caused<span> by an uneven temperature within something. </span>Convection currents<span>happen within the Earth's magma, water and air. It can happen in anything that is not solid and has parts that are cooler or warmer than other parts.</span>
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:
d.
Explanation:
Since, the capacitance( decreases )
therefore voltage between the plates(increases ).
Hence, option d is correct.
C =εA/d.
d is doubled, therefore C decrease ( inverse relation).
Answer:
8.08 x 10^-5 m
Explanation:
A = 2 mm^2 = 2 x 10^-6 m^2
Total number of electrons, N = 9.4 x 10^18
time, t = 3 s
n = 5.8 x 10^28 electrons/ m^3
Current, i = Q / t = N x e / t = (9.4 x 10^18 x 1.6 x 10^-19) / 3 = 0.5 A
Let vd be the drift velocity.
i = n e A vd
0.5 = 5.8 x 10^28 x 1.6 x 10^-19 x 2 x 10^-6 x vd
vd = 2.7 x 10^-5 m/s
Distance traveled by the electrons = velocity x time
= vd x t = 2.7 x 10^-5 x 3 = 8.08 x 10^-5 m
Answer:
1 and 3
Explanation:
because they are going up from 0