A science script on Electric current

 

electric current and its effects

There are three conditions for an electric current to flow: Ø a source of electric current, Ø an unbroken path and Ø a metal wire.

Properties of Electric Current

• We know that electric current is the result of the flow of electrons. The work done in moving the electron stream is known as electrical energy. Electrical energy can be converted into other forms of energy such as heat energy, light energy, etc. For example, in an iron box, electric energy is converted to heat energy. Likewise, the electric energy in a bulb is converted into light energy.
• There are two types of electric current known as alternating current (AC) and direct current (DC). The direct current can flow only in one direction, whereas the alternating direction flows in two directions. Direct current is seldom used as a primary energy source in industries. It is mostly used in low voltage applications such as charging batteries, aircraft applications, etc. Alternating current is used to operate appliances for both household and industrial and commercial use.
• The electric current is measured in ampere. One ampere of current represents one coulomb of electric charge moving past a specific point in one second.

1 ampere = 1 coulomb / 1 second

• The conventional direction of an electric current is the direction in which a positive charge would move. Henceforth, the current flowing in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery.

 

units of electricity

coulomb unit   columb unit of charge The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge. The coulomb was defined as the quantity of electricity transported in one second by a current of one ampere:  1 C = 1 A × 1 s The 2019 redefinition of the ampere and other SI base units fixed the numerical value of the elementary charge when expressed in coulombs, and therefore fixed the value of the coulomb when expressed as a multiple of the fundamental charge. In an International Systems, the unit of electric charge is the meter-kilogram-second-ampere, which is the basis of the SI system of physical units. Coulomb is abbreviated as C. Coulomb unit is of the electric charge.  We define Coulomb as the quantity of electricity transported in one second by a current of one ampere. This quantity was named Coulomb in the 18th–19th-century after a French physicist named Charles-Augustin de Coulomb, one Coulomb is approximately equal to 6.25 × 1018 electrons.

ampere unit "The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one meter apart in vacuum, would produce between these conductors a force equal to 2×10−7 newtons per meter of length."   As of the 2019 redefinition of the SI base units, the ampere is defined by fixing the elementary charge e to be exactly 1.602176634×10−19 C (coulomb),[6][9] which means an ampere is an electrical current equivalent to 1019 elementary charges moving every 1.602176634 seconds or 6.241509074×1018 elementary charges moving in a second. Prior to the redefinition the ampere was defined as the current that would need to be passed through 2 parallel wires 1 metre apart to produce a magnetic force of 2×10−7 newtons per metre.   The 2019 redefinition of the SI base units defined the ampere by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 × 10−19 when expressed in the unit C, which is equal to A⋅s, where the second is defined in terms of ∆νCs, the unperturbed ground state hyperfine transition frequency of the caesium-133 atom.[18] The SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere".[19] Conversely, a current of one ampere is one coulomb of charge going past a given point per second: {\displaystyle {\rm {1\ A=1\,{\text{C/s}}.}}} In general, charge Q is determined by steady current I flowing for a time t as Q = I t. Constant, instantaneous and average current are expressed in amperes (as in "the charging current is 1.2 A") and the charge accumulated (or passed through a circuit) over a period of time is expressed in coulombs (as in "the battery charge is 30000 C"). The relation of the ampere (C/s) to the coulomb is the same as that of the watt (J/s) to the joule.

Heating Effect of Electric Current

When our clothes are crumpled, we use the iron box to make our clothes crisp and neat. Iron box works on the principle of heating effect of current. There are many such devices that work on the heating effect.

When an electric current flows through a conductor, heat is generated in the conductor.

The heating effect is given by the following equation

H=I²RT

The heating effect depends on the following factor:

• The time ‘t‘ for which the current flows. The longer the current flows in a conductor more heat is generated.
• The electrical resistance of the conductor. Higher the resistance, the higher the heat produced.
• The amount of current. The larger the amount of current higher the heat produced.

If the current is small then the amount of heat generated is likely to be very small and may not be noticed. However, if the current is larger then it is possible that a noticeable amount of heat is generated.

State Coulomb’s law.

The magnitude of the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them.

some other effects

Magnetic Effect of Electric Current

Another prominent effect that is noticeable when an electric current flows through the conductor is the build-up of the magnetic field. We can observe this when we place a compass close to a wire carrying a reasonably large direct current, and the compass needle deflects. The magnetic field generated by a current is put to good use in a number of areas. By winding a wire into a coil, the effect can be increased, and an electromagnet can be made.

 

Chemical Effect of Electric Current

When an electric current passes through a solution, the solution ionizes and breaks down into ions. This is because a chemical reaction takes place when an electric current passes through the solution. Depending on the nature of the solution and the electrodes used, the following effects can be observed in the solution:

• change in the colour of the solution
• metallic deposits on the electrodes
• a release of gas or production of bubbles in the solution.