The electric field of an electromagnetic wave ina vacuum is ey= (20 v/m)sin((6.28x108)x -2πft), where x is in m and t is in s. what are the wave’s (a) wavelength, (b) frequency, and (c) magnetic field amplitude?

(a) 10 nm

(b) 1 Hz

(c) 20 V/m

Explanation

The equation of a progressive wave is given by:

                                y = Asin(kx ± ωt)

where;

A is the amplitude of the wave in meters

y(x,t) is the displacement in meters

k = 2π/λ is the propagation constant

ω = 2πf is the angular frequency in radian per seconds

The equation now becomes;

                                   y = Asin((2πx)/λ ± 2πft)

(a) Comparing Ey= (20 V/m)sin((6.28x10⁸)x -2πft) with the general equation

                                   (2πx)/λ = 6.28 × 10⁸

                                   λ = 2π / 6.28 × 10⁸

                                   λ = 1.0 × 10⁻⁸ m

                                   λ = 10 × 10⁻⁹ m

                                   λ = 10 nm

(b) Comparing Ey= (20 V/m)sin((6.28x10⁸)x -2πft) with the general equation

                                    2πft = 2πft    

                                         f = 1 Hz

(c) Comparing Ey= (20 V/m)sin((6.28x10⁸)x -2πft) with the general equation

                                     A = 20 V/m

increase masses, decrease separation

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.