The two things that must exist for an electric current to be produced are:
An electric potential between two bodies and a conducting path joining the bodies.
This comes from the fact that when there is a potential difference there is an electrical field and hence a force that makes some free charges to move in the conductor. For this reason, there's an electrical current.
Answer:
0.5 Amperes
Explanation:
Information that we have:
Power: 
Voltage: 
and we use the equation that relates this two quantities to the Current (I):

where I is the curent, P is the Power and V is the Voltage.
we substitute the values given for the Power and the Voltage to find the current:

the Current running into the bulb is 0.5 Amperes
Answer:
C
Explanation:
Because everything on Earth falls at the same speed, the masses of the balls do not matter. Since the acceleration due to gravity is constant, their speeds will both be increasing at the same rate, and therefore the difference in speeds would remain constant until they hit the ground. Hope this helps!
Answer:
GIVEN
u is 40m/s and v=60m/s
time is 4s
therefore acceleration =60-40/4
=20/4=5m/s^2
b)next 2 sec=70m/s
When balanced forces act on an object at rest, the object will not move. If you push against a wall, the wall pushes back with an equal but opposite force. Neither you nor the wall will move. Forces that cause a change in the motion of an object are unbalanced forces.