Answer:
1. A <em>series circuit </em>is a closed circuit which has all loads connected in a row and there is only one path for the current to flow.
2. The <em>Ohm's Law </em>state that a current flow through a resistor is directly proportional to the voltage across it 
3. A <em>parallel circuit </em>is a closed circuit divided into branches that it has two o more paths for the current to flow and the loads are parallel to each other which mean the voltage across them is the same for all loads.
Answer:

Explanation:
The power provided by a resistor (wire in this case) is given by:
.
The resistance of a wire is given by:

Where for the resistivity the one of the copper should be used:
.
The area A is that of a circle, which written in terms of its diameter is:

Putting all together:

Which for our values is:

Answer: I = 3.6 m3
(C)
Explanation:
moment of inertia for spherically shaped object around it's center is given as
I = (2/5) mr²
substituting the r = 3m²
I = (2/5)*(9) m3
I = 3.6 m3
Answer:2155 J
Explanation:
Given
Change in Internal energy
i.e. decrease in Internal Energy
Heat added to system 
According First law for a system



Thus 2155 J of work is done by system
Answer:
The kinetic energy of the proton at the end of the motion is 1.425 x 10⁻¹⁶ J.
Explanation:
Given;
initial velocity of proton,
= 3 x 10⁵ m/s
distance moved by the proton, d = 3.5 m
electric field strength, E = 120 N/C
The kinetic energy of the proton at the end of the motion is calculated as follows.
Consider work-energy theorem;
W = ΔK.E

where;
K.Ef is the final kinetic energy
W is work done in moving the proton = F x d = (EQ) x d = EQd




Therefore, the kinetic energy of the proton at the end of the motion is 1.425 x 10⁻¹⁶ J.