Answer: a) 274.34 nm; b) 1.74 eV c) 1.74 V
Explanation: In order to solve this problem we have to consider the energy balance for the photoelectric effect on tungsten:
h*ν = Ek+W ; where h is the Planck constant, ek the kinetic energy of electrons and W the work funcion of the metal catode.
In order to calculate the cutoff wavelength we have to consider that Ek=0
in this case h*ν=W
(h*c)/λ=4.52 eV
λ= (h*c)/4.52 eV
λ= (1240 eV*nm)/(4.52 eV)=274.34 nm
From this h*ν = Ek+W; we can calculate the kinetic energy for a radiation wavelength of 198 nm
then we have
(h*c)/(λ)-W= Ek
Ek=(1240 eV*nm)/(198 nm)-4.52 eV=1.74 eV
Finally, if we want to stop these electrons we have to applied a stop potental equal to 1.74 V . At this potential the photo-current drop to zero. This potential is lower to the catode, so this acts to slow down the ejected electrons from the catode.
Answer:
2.64N
Explanation:
Force = mass * acceleration
Given
mass = 4kg
distance = 1.9m
Time t = 2.4s
Get the acceleration using the equation of motion
S = ut + 1/2at²
1.9 = 0 + 1/2a(2.4)²
1.9 = 5.76a/2
1.9 = 2.88a
a = 1.9/2.88
a = 0.66m/s²
Get the magnitude of the force
Force = 4 * 0.66
Force = 2.64N
Hence the net force acting on the fish is 2.64N
Explanation:
1. The entire span of possible sound waves is called the acoustic spectrum. It is subdivided into infrasonic sounds, audible sounds, and ultrasonic sounds.
2. The difference between a musical note and another note at twice the frequency is called an octave.
3. Sound intensity varies with the inverse square of distance.
