Answer:
C. It is caused by flowing negatively charged particles.
Explanation:
Current electricity is caused by flowing negatively charged particles. The negatively charged particles that are responsible for the flow of electricity are called electrons.
The force is equal at all points in the field as the field lines are parallel in a uniform field. So, negatively charged particles will move in the opposite direction to the current.
Hence, the correct answer is "C. It is caused by flowing negatively charged particles."
 
        
             
        
        
        
Answer:
6.71 × 10^8 mi/hr
Explanation:
Light is usually defined as an electromagnetic wave that is comprised of a definite wavelength. It is of both types, visible and invisible. The light emitted from a source usually travels at a speed of about 3 × 10^8 meter/sec. This speed of light is commonly represented by the letter 'C'.
To write it in the metric system, it has to be converted into miles/hour.
We know that,
1 minute = 60 seconds
60 minutes = 1 hour
1 kilometer = 1000 meter
1 miles = 1.6 kilometer
Now, 
= 
= 1.08 × 10^12 m/ hr (meter/hour)
= 
= 6.71 × 10^8 mi/hr (miles/hour)
Thus, the value for speed of light (C) in metric unit is 6.71 × 10^8 mi/hr.
 
        
             
        
        
        
Solution :-
Given : 
Distance 1 = 30 km
Distance 2 = 70 km
We know that speed = distance/time
and, Average speed = total distance/total time taken
When the train acquired a speed of 30 km/hr, the time taken = 30/30 = 1 hour
Average speed = 9distance 1 + distance 2)/(time 1 + time 2)
AS time 2 or t2 is time taken for the second part of the journey of 70 km 
⇒ 40 = 100/(1 + t2)
⇒ 40 + 40t2 = 100
⇒ 40t2 = 100 - 40
⇒ 40t2 = 60
⇒ t2 = 60/40
⇒ t2 = 1.5 
So, t2 or time taken to travel the second part of the journey is 1.5 hours.
Speed of the second part of the journey = distance 2/time 2
⇒ 70/1.5
⇒ 46.666 km/hr or 46.7 km/hr. 
 
Hence the answer is = 46.666 km/hr or 46.7 km/hr. 
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The speed downwards is 7 + (3*9.8) 
7+ 29.4 = 36.4 m/s