Which of the following does  notaccurately describe transistors?                 a.  both npn and pnp transistors consist of an emitter, base, and collector.      b.  both npn and pnp transistors consist of a base composed of an n-type material.      c.  both npn and pnp transistors consist of p-type and n-type material.      d.  both npn and pnp transistors operate in the same manner but with interchanged terminals and opposite directions of voltage and current. 

b.transmitters send radio waves, and receivers capture radio waves.

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.