Electric Current Formula
There are three types of material, insulator and semiconductor.
- Conductor => Allows to flow of current
- Insulator => Do not allows the flow of current
- Semi conductor => Conductivity lies between conductor and insulator.
Now what is electric current,
The rate of flow of charges through conductor is called current. That means continuous flow of electrons in a circuit is called as electric current. The ammeter is used to measure current and connected in series in a circuit.
Consider any conducting material in which large number of free electrons are moving from one atom to the other atom randomly. The direction of flow of current in wire is from negative terminal to positive terminal of battery and the direction of electron (charge) is opposite to the flow of current.
Current is rate of flow at electrons through the circuit current is denoted by I.
Mathematically,
I = Q/t
I = Q/t ——– (1)
Where,
I = Electrio current (A)
Q = Electric charge (C)
t = Time (t)
SI unit electric current is Amperes (A).
The charge is measured in coulombs and time in seconds, so current coulomb/sec i.e. Amperes (A).
The charge at one electron is 1.6 × 10-19 C.
1 mA (miliampere) = 10-3A
1 µA (microampere) = 10-6A
Numericals:
(1) How many electrons are pass through the bulb in 3 minutes, if 300 mA of current pass through the bulb?
Given:
I = 300 mA = 0.3 A
t = 3 min = 3 × 60 = 180 sec.
Q =?
I = Q/t
0.3 = Q/180
Q = 0.3×180
Q = 54 c
1C = 6×1018
So, 54 × 6 × 1018 = 324 × 1018
Electron passes through the bulb is 324 × 1018
(2) If the amount of charge passing through the cell in 4 minutes is 480 C then calculate the current passing through the cell?
Given:
Q = 480 C
t = 4 min
I =?
I = Q/t
I = 480c/4×60 sec
I = 480/240
I = 2A
Current passing through the cell is 2A.