Part a: how many excess electrons must be distributed uniformly within the volume of an isolated plastic sphere 26.0cm in diameter to produce an electric field of 1500 n/c just outside the surface of the sphere? part b: what is the electric field at a point 13 cm outside of the surface of the sphere?

Q = 28.17 x 10⁻¹⁰ C

E= 375 N/C

Explanation:

Let Q be the charge on plastic sphere.

Field on the surface =k x charge / radius²

Putting the values we get

Q = 28.17 x 10⁻¹⁰ C

No of electrons = Charge / charge on one electron

=

= 7 x 10¹⁰

Electric field at 13 cm

=

E= 375 N/C

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.

b.a device that inputs heat into a cool object