Answer: a) for 150 Angstroms 6.63 *10^-3 eV; b) for 5 Angstroms 6.02 eV
Explanation: To solve this problem we have to use the relationship given by De Broglie as:
λ =p/h where p is the momentum and h the Planck constant
if we consider the energy given by acceleration tube for the electrons given by: E: e ΔV so is equal to kinetic energy of electrons p^2/2m
Finally we have:
eΔV=p^2/2m= h^2/(2*m*λ^2)
replacing we obtained the above values.
Answer:
constant volicty of the pumper when they hit ground 7.03-/s
Answer:
The atomic number 26(iron) is the threshold value below which the fusion might occur.
Explanation:
Nuclear fusion is a reaction in which two or more nuclei are combined to form one or more different atomic nuclei and subatomic particles.
Energy released in a fusion reaction is because of a key feature of nuclear matter called the binding energy which is a measure of the efficiency with which its constituent nucleons are bound together.
As we go up in atomic number, the energy released per nuclei goes down until it hits a minimum which is for atomic number 26 (iron) and fusion is not possible.
(a) The force exerted by the electric field on the plastic sphere is equal to

where

is the charge of the sphere and E is the strength of the electric field. This force should balance the weight of the sphere:

where m is the mass of the sphere and g is the gravitational acceleration.
Since the two forces must be equal, we have:

and so we find the intensity of the electric field

(b) Now let's find the direction of the field. The electric force must balance the weight of the sphere, which is directed downward, so the electric force should be directed upward. Since the charge is negative, the force is opposite to the electric field direction, and so the direction of the electric field is downward.