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.
Since the law of gravitation is an inverse square law if you
quadruple the radius the f will drop by a factor of 16 SO the object would
weigh 200/16 = 12.5N
In other words, as the distance, or radius, quadruples the
weight becomes 1/16 of the original weight. Just plug in 4 for r and when you
square it you get 16. The numerator is 1 so that is how the weight becomes
1/16.
Answer:
(9/35) = 0.257
Explanation:
Box contains 9 new light bulbs and 6 used light bulbs, total number of bulbs = 15.
Probability of selecting two bulbs; a new light bulb and then, a used light bulb in that order = [(probability of selecting a new bulb) × (probability of selecting a used bulb from the rest)] = [(9/15) × (6/14)] = (9/35) = 0.257
<span>Based
on Newton's law of universal gravitation, the equation for the
gravitational force exerted by an object on another object is given by:
F = Gm1m2/(r^2)
where G is the universal gravitational constant, F is the gravitational
force exerted, m1 is the mass of the first object, m2 is the mass of the
second object, and r is the separation distance between the two
objects.
If the mass of both objects were doubled, then we would have: m1' * m2' =
(2m1) * (2m2) = 4m1m2. Assuming r stays constant (G is a constant so
that won't change anyway), then this means that the new force will be 4
times greater, ie 8N * 4 = 32N of gravitational force. </span>
