A 65-turn coil has a diameter of 14 cm. Find the magnitude of the emf induced in the coil (in V) if it is placed in a spatially uniform magnetic field of magnitude 0.65 T so that the face of the coil makes the following angles with the magnetic field, and the magnetic field is reduced to zero uniformly in 0.2 s.

The value is  

Explanation:

From the question we are told  that

    The number of turns is  n =  65

    The diameter is  

    The magnetic field is  

    The time taken for the magnetic field to be reduced to is

Generally the magnitude of the induced emf is mathematically represented as

Here A is the area of the coil which is mathematically represented as

=>    

=>    

So

=>      

it may be wrong but i think its a

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.