2. Cell phones work by receiving and emitting radiation in the range of 1.9-2.2 Giga Hertz (GHz). This is about 1.9 X 109 -2.2 X 109 Hz.
A) Based on this information, calculate the wavelength of this radiation.
B) What type of electromagnetic radiation do cell phones use?

A) 0.136 - 0.158 m

B) Microwaves

Explanation:

A)

For an ectromagnetic wave, there is a relationship between its frequency and its wavelength, contained in the wave equation:

where

is the wavelength of the wave

 is the speed of light in a vacuum

f is the frequency of the wave

For the waves in this problem, we have:

is the minimum frequency

is the maximum frequency

Therefore, the range of corresponding wavelengths is:

B)

Electromagnetic waves are oscillations of the electric and the magnetic field occurring in a plane perpendicular to the direction of motion the wave.

All electromagnetic waves travel in a vacuum always at the same speed, the speed of light ( ).

Electromagnetic waves are classified into 7 different types, according to their wavelength and frequency. From the longest to the shortest wavelength, we have:

Radio waves (>1 m)

Microwaves (1 mm - 1 m)

Infrared (750 nm - 1 mm)

Visible light (380 nm - 750 nm)

Ultraviolet (10 nm - 380 nm)

X-rays (0.01 nm - 10 nm)

Gamma rays (<0.01 nm)

Therefore, we see that the waves in this problem (of wavelength between 0.136 and 0.158 m) are classified as microwaves.

this a false

explanation:

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.