Answer:
Current flows in a resistor-capacitor circuit because of the varying electric field across the plates of a capacitor induced by an AC voltage source <em>(displacement current)</em>
Explanation:
In a capacitor, current does not flow the same way it does in a circuit, that is through conduction. This is because there is a highly resistive material in between the plates of the capacitor. Rather current flows through a phenomenon called displacement current.
Because of change in charge accumulation with time above the plates, the electric field changes causing the displacement current.
Displacement current arises due to the flow of electrons as a result of the varying magnetic fields set up on the plates of the capacitor when supplied with an AC voltage. It is important to note that a DC voltage does not induce any displacement current.
<em>Through this, phenomenon discovered by Maxwell, current is able to flow in a resistor-capacitor circuit despite the absence of an electrically conductive path through the plates.</em>
Answer:
Friction between the box and the floor is 25N to the left.
Explanation:
According to Newton's second law of motion, the net force acting on an object is equal to the produce between the object's mass and its acceleration:
where
m is the mass of the object
a is its acceleration
In this problem, we have two forces acting on the object:
- The applied force, F = 25 N, to the right
- The force of friction 
, opposing the motion of the box, so to the left
So we can write the net force as
Also, we know that the box is moving at constant speed: this means its acceleration is zero, so
Therefore
WHich means:
And therefore,
which means that the force of friction is also 25 N.
Answer:
The charge in each ball will be 3 * 10^-12 C
Explanation:
(Assuming the correct charge of the second ball is 8 * 10^-12)
When the balls are brought in contact, all the charges are split evenly among then.
So first we need to find the total charge combined:
(-3 * 10^-12) + (8 * 10^-12) + (4 * 10^-12) = 9 * 10^-12 C
Then, when the balls are separated, each ball will have one third of the total charge, so in the end they will have the same charge:
(9 * 10^-12) / 3 = 3 * 10^-12 C
So the charge in each ball will be 3 * 10^-12 C
The two-second rule.
It is a common guideline to follow while driving.
It means that any given driver should be AT LEAST two seconds behind any vehicle that is driving in front of his vehicle. It might apply for any kind of vehicle.
Answer:
The power
Explanation:
We know that the work definition is given by the following expression:
W = F * d
where:
F = force [Newtons] [N]
d = distance [meters] [m]
W = work [Joules]
And the expression that defines the work done by unit of time is called - <u>Power</u>, therefore:
P = W/t
where:
P = power [watts] [w]
W = work [Joules] [J]
t = time [seconds] [s]
