Answer:
1. Reflection
2. travel from one medium to another
3. Same waves to travel in opposite direction.
Explanation:
1. When a wave strikes a solid barrier, it bounces back in the same medium. This wave behavior of bouncing back is known as reflection. Its like a basketball hitting a backboard. The ball bounces back at the same angle as it was incident. ∠i = ∠r
2. For refraction to occur in a wave, the wave must travel from one medium to another. When light travels from through mediums of different optical densities, it bends. The wave bends away normal when it enters from denser medium to rarer medium. The wave bends towards the normal when it enters from rarer to denser medium. The angle of refraction and angle of incidence are related by Snell's law.

3. The formation of standing wave requires two same waves to travel in the opposite direction and interfere. The incident wave and reflected wave when interfere, form standing waves. There waves are also resonances or harmonics. A standing wave oscillates at one place and does not transfers any energy.
D. Extreme temprature and cloudy waters
Answer:
3.88 * 10^(-15) J
Explanation:
We know that the Potential energy of the electron at the beginning of its motion is equal to the Kinetic energy at the end of its motion, when it reaches the plates.
First, we get the potential and potential energy:
Electric potential = E * r
E = electric field
r = distance between plates
Potential = 2.2 * 10^6 * 0.011
= 2.42 * 10^4 V
The relationship between electric potential and potential energy is:
P. E. = q*V
q = charge of electron = 1.602 * 10^(-19) C
P. E. = 2.42 * 10^4 * 1.602 * 10^(-19)
P. E. = 3.88 * 10^(-15) J
Acceleration will be 9.81 if it goes downwards. If it accelerates upwards it will be -9.81m/s^2