According to Fleming's left-hand rule, the force on wire 2 acts in the plane of paper perpendicular to wire 2, directed towards wire 1. Similarly, wire 1 also experiences the same force towards wire 2. Thus, both the conducting wires attract each other with the same force F.
One ampere can be defined as the amount of current flowing through two parallel conductors, which are in the same direction or opposite directions, placed at a distance of one metre in free space, and both the wires attract or repel each other with a force of 2 x 10^-7 per metre of their lengths. 

A moving charge produces both electric and magnetic fields, and an oscillating charge produces oscillating magnetic and electric fields. These oscillating electric and magnetic fields with respect to space and time produce electromagnetic waves. 
The propagation of electromagnetic waves can be shown as:


                                                  OR

Maxwell's generalization of ampere's circuital law given by,


Consider that a parallel capacitor C is charging in a circuit. 
The magnitude of electric field between the two plates will be, 
 , is perpendicular to the surface of the plate. 
Electric flux through the surface will be, 

Voltage of the source is given by, 
V = V_o sin ωt 
                                           
Let current of the source be I = I_o sin ωt
Maximum voltage across R is V_R = V_o R, represented along OX
Maximum voltage across L = V_L  = I_O X_L, represented along OY and is 90^o ahead of I_o.
Maximum voltage across C = V_C = I_o X_C, represented along OC and is lagging behind I_o by 90^o
Hence, reactive voltage is V_L - V_C, represented by OB'

the vector sum of V_R, V_L and V_C is resultant of OA and OB', represented along OK.
OK = V_o = 
i.e., V_o = 

Impedance, Z = 
When, X_L = X_C ,  the voltage and current are in the same phase. 
In such a situation, the circuit is known as non-inductive circuit. 
ii) 
Given,
Power factor, P₁ = R/Z

Thus, 

i) A transformer is a device that changes a low alternating voltage into a high alternating voltage or vice versa. 
Transformer works on the principle of mutual induction. 
A changing alternate current in primary coil produces a changing magnetic field, which induces a changing alternating current in secondary coil. 
 
Energy losses in transformer: 
Flux leakage due to poor structure of the core and air gaps in the core.
Loss of energy due to heat produced by the resistance of the windings.
Eddy currents due to alternating magnetic flux in the iron core, which leads to loss due to heating. 
Hysteresis, frequent and periodic magnetisation and demagnetization of the core, leading to loss of energy due to heat.
ii)
a)  Number of turns in secondary coil is given by, 

 
b) Current in primary is given by, 

i) 
Drift velocity is the average velocity of the free electrons in the conductor with which they get drifted towards the positive end of the conductor under the influence of an external electric field.
ii) 
Free electrons are in continuous random motion. They undergo changethey undergo change in direction at each collision and the thermal velocities are randomly distributef in all directions. 


Electric field, E = -eE 
Acceleration of each electron,          ... (2) 
Here, 
m = mass of an electron
e = charge on an electron
Drift velocity is given by, 
 
Electrons are accelerated because of the external electric field. 
They move from one place to another and current is produced.
For small interval dt, we have
I dt = -q ; where q is the total charge flowing
Let, n be the free electrons per unit area. Then, total charge crossing area A in time dt is given by,
Idt = neAvd dt
Substituting the value of v_d, we get 
I.dt = neA  
Current density, J  = 
From ohm's law, we have
J = 
Here,  is the conductivity of the material through whic the current is flowing,
Thus, 

iii) 
Alloys like constantan and manganin are used for making standard resistors because:
a) they have high value of resistivity
b) temperature coefficient of resistance is less.