Explanation:
The given data is as follows.
Electric field between plates without dielectric, 
Electric field between the plates with dielectric,
.
Permittivity of free space,
= 
Now, we will determine the charge density as follows.

= 
= 
Thus, we can conclude that the charge density on each surface of the dielectric is
.
Just from that one observation, choice-B
would be a reasonable conclusion.
Answer:
formula used K=F/∆l
∆l is the elongation of the spring
- F=10N
- ∆l=20mm===> 0.02m
- K=10N divided 0.02m= 500N/m
Answer: This is called the Doppler effect, where waves shift frequency and wavelength as the source travels towards you (higher frequency, shorter wavelength) or away from you (lower frequency, longer wavelength)
Explanation:
hoped this helped have a good day :)