Two stationary point charges of 3.00 nC and 2.00 nC are separated by a distance of 60.0 cm. An electron is released from rest at a point midway between the charges and moves along the line connecting them. Part A What is the electric potential energy of the electron when it is at the midpoint

U =-2.39*10^-18 J

Explanation:

In order to calculate the electric potential energy of the electron you use the following formula:

          (1)

k: Coulomb's constant = 8.98*10^9Nm^2/C^2

r: distance between charges

In this case the electron is at point midway between two charges, then the electric potential energy is the sum of two contributions:

e: charge of the electron = 1.6*10^-19C

q1: charge 1 = 3.00nC = 3.00*10^-9C

q2: charge 2 = 2.00nC = 3.00*10^-9C

r: distance to each charge = 60.0cm/2 = 30.0cm = 0.3m

If you consider that the electron is at the origin of coordinates, with the first charge in the negative x axis, and the other one in the positive x axis, you have:

The electric potential energy of the electron is -2.39*10^-18 J

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.