Electric Current Fundamentals and Circuits - Class XII

1 ampere means 1 coulomb of charge flows per second. Since each electron carries 1.6 × 10^-19 C, the number of electrons needed is 1 ÷ (1.6 × 10^-19) = 6.25 × 10^18. Option A correctly shows this calculation.

Electric charge is quantized, meaning any charge must be an integer multiple of the elementary charge e = 1.610^-19 C. Option A (1.9010^-18) is not a multiple of 1.6*10^-19 (1.9/0.16 = 11.875), making it physically impossible.

A 3 pin plug consists of three pins (hence the name). Each pin must be correctly connected to the three wires in the electrical cable. Each wire has its own specified color so as it can be easily identified.
The LIVE wire is RED OR BROWN. This is connected to a fuse on the live pin. The electric current uses the live wire as its route in.
The NEUTRAL wire is BLUE OR BLACK. This is the route the electric current takes when it exits an appliance; it is for this reason the neutral wire has a voltage close to zero.
The EARTH wire is GREEN OR  YELLOW and connected to the earth pin. This is used when the appliance has a metal casing to take any current away if the live wire comes in contact with the casing.

A switch opens or closes an electrical circuit. If the circuit is open, no electricity flows. If the circuit is closed, electricity flows through the circuit. 
Example:
A light switch is commonly used. When you turn the switch on, the circuit closes and electricity flows through the light. When you turn the switch off, the circuit is opened and the flow of electricity stops, making the light go out. 
In our homes, we receive supply of electric power through a main supply (mains), either supported through overhead electric poles or by underground cables.The live wire and neutral wire, coming from the electric pole, enter a box fitted just outside our house which has a main fuse.
The live wire is connected to the switch because, the live wire carries a voltage of 220 V and the passage of this voltage can be disabled by switching of the circuit.

In electricity generation A generator is a device which uses mechanical energy to produce electrical energy which flows in form of electric current in circuits. hence Generator can produce current.

Electric current flows from positive electrode of cell to negative electrode of cell, i.e., from high potential to low potential.

The current in the wire is due to the drifting of electrons inside a wire in a direction opposite to the flow of electrons. During their drifting they collide with their atoms vibrating about their mean position and lose some of kinetic energy to the vibrating atoms. 
The electrons are negatively charged particles and so, the electrons move towards the positively charged terminal from the negatively charged terminal.
Hence, the statement is true as the conventional direction of flow of current is from positive terminal to negative terminal of the cell.

An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in a plasma.
The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.

Current is measured in Coulomb/sec or Ampere. 

The direction of an electric current is by convention the direction in which a positive charge would move. Thus, thecurrent in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction.

Current travels in a conductor at a speed approximately equal to speed of light i.e. $3\times 10^8$ $ms^{-1}$.

(A) Option:- Electricity can be created. This statement is false because electricity is basically a form of energy that cannot be created nor be destroyed 

In cells, electrons move from negative electrode to positive electrode and an electron has negative charge. So, we can say that negative charge flows from negative electrode to positive electrode. But, by convention flow of charges are measured only through positive charges.When an electron moves from point A to point B,an equal amount of positive charge moves from point B to point A.

Electric current is defined as the flow of electrons.

As unlike charges attract each other and like charges repel each other. Thus in electrolysis, positive ions move towards the negative electrode whereas negative ions move toward the positive electrode.Hence option B is correct.

In a DC circuit , when switch is closed , the free electrons in wire are drifted from negative plate of the battery to positive plate.

Conventionally, the current flows in the direction of flow of positive charge or opposite to the flow of negative charge (electrons).

Direction of current is taken as direction of flow of positive charge.
Opposite to the direction of flow of electrons.

Electrons are negatively charged particles. So, by convention, the direction of current is considered as the opposite to the direction of motion of electrons.

Answer is A.
When an electric field is applied across the metallic conductors the randomly moving electrons are subjected to electrical forces along the direction of the field. Due to this field, the electrons do not give up their randomness of motion, but they will be shifting towards higher potential. That means the electrons will drift towards higher potential along with their random motions. 
In semiconductors, in addition to electrons, the travelling vacancies in the valence-band electron population (called 'holes'), act as mobile positive charges and are treated as charge carriers. Electrons and holes are the charge carriers in semiconductors.
Hence, electric current is due to drift of electrons in metallic conductors.

In series connection same current will flow through each one of them.

Conventional Current assumes that current flows out of the positive terminal, through the circuit and into the negative terminal of the source. This was the convention chosen during the discovery of electricity.
Not from high electron density to low electron density.

By convention a positively charged body is always at a higher potential as compared to negatively charged body . If positive charges like protons or positive ions are free to move they would move from higher potential point to lower potential point.

Current through a resistance (R) is given by, $V=i*R _{eq}$
$i=150/30$
$i=5$ ampere

Charge flows from a higher potential to a lower potential. Since sphere A is at 100V and sphere B is at 50V, charge will flow from A to B until they reach the same potential.

Using the right-hand grip rule for a downward current, the magnetic field lines form circles around the wire. For an observer looking at the wire, the field at a point between them and the wire points to the right.

Drift velocity v_d = I / (nAe). The number density n = (density * Avogadro's number) / atomic weight. Calculating n for Aluminum and substituting into the formula yields approximately 1.2*10^-4 m/s.

When a switch is closed, the electric field propagates through the circuit at nearly the speed of light, causing electrons everywhere in the wire to start drifting almost simultaneously. The tiny delay before the bulb lights up is set by how fast the electromagnetic field travels through the conductors, not the very slow drift speed of the electrons themselves.

Using right-hand rule for upward current: magnetic field circles the wire. For a horizontally directed electron beam approaching the wire, force F = -e(v × B). The force direction depends on whether beam approaches from left or right of wire - not specified. Assuming beam approaches from left side of wire (viewer's perspective), it deflects vertically downward perpendicular to paper plane.

The magnetic field B of an infinite wire is B = (mu_0 * I) / (2 * pi * r). Rearranging for I: I = (B * 2 * pi * r) / mu_0. Given B = 10^-5, r = 0.1m, and mu_0 = 4pi10^-7, I = (10^-5 * 2 * pi * 0.1) / (4 * pi * 10^-7) = 5 A.

Using Ampere's Law, integral(B dl) = mu_0 * I_enclosed. If current density J = kr, then I_enclosed = integral(J * 2pir dr) from 0 to r. Solving this and relating k to total current I gives the field B = (mu_0 * I * r^2) / (2 * pi * R^3).

By convention, the direction of conventional electric current is defined as the flow of positive charge, which is from the positive terminal to the negative terminal.

The electric field E between parallel plates is given by E = V / d. Given V = 9 V and d = 0.001 m, E = 9 / 0.001 = 9000 V/m.

Total charge Q = I * t = 0.32 A * 3600 s = 1152 C. Number of electrons n = Q / e = 1152 / 1.610^-19 = 7.210^21.

Current I = J dot A. Given J = (2j + 2k) A/m^2 and A = (2i + 4j) mm^2 = (2i + 4j) * 10^-6 m^2. The dot product is (02 + 24 + 2*0) * 10^-6 = 8 * 10^-6 A = 8 microA.

Current I = q / t. Total charge q = 10^12 * 1.610^-19 = 1.610^-7 C. Time t = 60 s. I = 1.610^-7 / 60 = 2.6710^-9 A.

Current I = q / t = (n * e) / t = (7.510^15 * 1.610^-19) / 10 = 1.2*10^-4 A.

In the question, it is given that the charge of an electron is $e=1.6\times { 10 }^{ -19 }\quad C$.

Ohm's law states that voltage drop across conductor is proportional current in it.

$R=\dfrac{E}{I}$

Current is defined as charge flow per unit time .

Resistance $R=\rho l/A, A=\pi d^2/4$ is directly proportional to the length and inversely proportional to the Area, i.e., directly proportional to the square of the diameter.

The cross-sectional area of the wires will affect the amount of resistance. Wider wires have a greater cross-sectional area. Water will flow through a wider pipe at a higher rate than it will flow through a narrow pipe. This can be attributed to the lower amount of resistance that is present in the wider pipe. In the same manner, the wider the wire, the less resistance that there will be to the flow of electric charge. When all other variables are the same, charge will flow at higher rates that is, more current through wider wires with greater cross-sectional areas than through thinner wires.
Hence, the 15 A rated wire is the thicker wire as more amount of current flow through it than the 5 A rated wire.

Inside the battery or cell, the positive charge move from negative terminal (lower potential) to positive terminal (higher potential) of the battery. While in external circuit the positive charge move from positive terminal to negative terminal of the battery.Hence correct option is C

Consider a conductor of length of $L$ and cross sectional area $A$. 

Sulphate ions move toward zinc electrode.
Oxidation half reaction occurs at anode.
$\displaystyle Zn \rightarrow Zn^{2+} +2e^-$
Positively charged Zn(II) ions enter anode solution. To maintain electrical neutrality, sulphate ions move toward zinc electrode.

Conventionally, movement (flow) of positive charge is considered and because, unlike charge repel each other, positive charge moves from positive electrode to negative electrode inside the cell. Hence option A is correct.

The current in the wire is due to the drifting of electrons inside a wire in a direction opposite to the flow of electrons. During their drifting they collide with their atoms vibrating about their mean position and lose some of kinetic energy to the vibrating atoms. The electrons are negatively charged particles and so, the electrons move towards the positively charged conductor A.
Hence, the direction of the flow of electrons in the copper wire is from B to A.

The chemical reaction due to passage of electric current depends on electrodes.
For example, during electrolysis of aqueous copper sulphate solution using platinum electrodes will give oxygen gas at anode.
On the other hand, during electrolysis of aqueous copper sulphate solution using copper electrodes will oxide Cu to Cu(II) ions at anode.

Conventionally the direction of flow of current is taken to be the direction of flow of positive charges.

Let number of electrons per second be n.
Given,
$e = 1.6 \times 10^{-19} C$ ,  $n =50 $
The current is defined as rate of flow of charge,
$I = \dfrac{q}{t} $ 
Hence,
$I = n \times e $

Conventional Current assumes that current flows out of the positive terminal, through the circuit and goes into the negative terminal of the source.

energy of the whole system will be conserved .

$R=\dfrac {V^2}{P}=\dfrac {(60^2)}{220}$
$=806.66 \Omega$
$I=\dfrac {P}{V}$
$=\dfrac {6-0}{220}=0.27$

According to the first law of electrolysis the mass of of substance liberated at cathode is proportional to the quantity of electric charge passed through it or indirectly it's proportional to the quantity of  electricity  passed.