The basic relationship between frequency of an electromagnetic wave and wavelength of the wave is

where

is the speed of light.
Manipulating the equation, we can rewrite it as

The frequency of the wave in our problem is

so if we use the previous formula, we find the correspondant wavelength:
Answer:
E = 1000 x
Explanation:
The electric potential and the electric field are related by the formula
dV = - E . dx
Bold represents vectors.
The point represents the scalar product, in this case we calculate the electric field in the x-axis and the potential is also in this axis so the scalar product is reduced to the algebraic product
E = dV /dx
Let's make the derivative
E = - 2ax
Let's replace the values
E = -2 (-500) x
E = 1000 x
Answer with Explanation:
We are given that
A=3i-3j m
B=i-4 j m
C=-2i+5j m
a.


Compare with the vector r=xi+yj
We get x=2 and y=-2
Magnitude=
units
By using the formula 
Direction:
By using the formula
Direction of D:
b.E=-A-B+C


units
Direction of E=
a.) Relative velocity = velocity of car B - velocity of car A
= 19 - 14
= 5 m/s
Hope this cleared your doubt, feel free to ask any question regarding this and have a nice day ahead! :)