The flow of Direct current (DC) is constant and flows in one direction. Most digital electronics make use of DC. Alternating current (AC) periodically flows in reverse and is mostly used to deliver power to houses, buildings and the like. With that alone, you can already rule out A, C and D.
The answer would then be B. constant, periodically reversing.
Answer:
By the use of slow motion camera.
Explanation:
Visually, it is very hard to differentiate between an ac and dc power supply. But Since, we that In Ac supply polarity changes 100 times in a second ( because frequency of ac supply is 50 Hz generally). Whereas, Dc gives a steady power supply. So, in slow motion camera we can easily capture the flickering light tubes which won't happen in case of dc supply.
Answer:
The cathode ray is deflected vertically to the fluorescent screen
Explanation:

Answer:
12.5 m/s
Explanation:
In a acceleration time graph the area under the curve gives the change in velocity of the object. Here object starts at rest and therefore initial velocity is 0. After 5 seconds acceleration is 5m/s2.
change in velocity=area under the curve
change in velocity= 0.5*acceleration* change in time
v-0=0.5*5*5
v=12.5 m/s
Answer: The resultant displacement vector is 5.6km