Two parallel plates have equal and opposite charges. When the space between the plates is evacuated, the electric field is E= 3.50×105 V/m . When the space is filled with dielectric, the electric field is E= 2.40×105 V/m .

What is the charge density on each surface of the dielectric?

Explanation:

The given data is as follows.

     Electric field between plates without dielectric,

   Electric field between the plates with dielectric, .

  Permittivity of free space, =

Now, we will determine the charge density as follows.

                 =

                 =

Thus, we can conclude that the charge density on each surface of the dielectric is .

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.