Answer:
1. Electromagnetic waves travel in a vacuum whereas mechanical waves do not.
2. The ripples made in a pool of water after a stone is thrown in the middle are an example of mechanical wave. Examples of electromagnetic waves include light and radio signals.
3. Mechanical waves are caused by wave amplitude and not by frequency. Electromagnetic Waves are produced by vibration of the charged particles.
4. While an electromagnetic wave is called just a disturbance, a mechanical wave is considered a periodic disturbance.
Explanation:
Explanation:
Given that,
Terminal voltage = 3.200 V
Internal resistance 
(a). We need to calculate the current
Using rule of loop


Where, E = emf
R = resistance
r = internal resistance
Put the value into the formula


(b). We need to calculate the terminal voltage
Using formula of terminal voltage

Where, V = terminal voltage
I = current
r = internal resistance
Put the value into the formula


(c). We need to calculate the ratio of the terminal voltage of voltmeter equal to emf


Hence, This is the required solution.
Refraction
the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density.
Answer:
Distance of 400m.
Explanation:
Use your kinematics equation to solve for distance (we can use kinematics b/c acceleration is constant).
d = (initial velocity x time) + 1/2 at^2
d = (20 x 10) + 1/2 (4) (10)^2
d = 200 + 200
d = 400 m