What is electric current?
CURRENT🔥
Electric current is the time rate of flow of electric charge along a conductor.
Current is produced when an electric charge flow from one point to another in a circuit.
The s.i .unit of current is ampere and the symbol is A. For current, I is used.
All this are the most important point that must note✍️✍️
AMPERE🔥
Ampere can be defined as the flow of one Coulomb of charge in one second. It is the unit of current.
COULOMB🔥
Coulomb is defined as the quantity of electricity that flow through a conductor in one second when the current through the conductor is one ampere. Coulomb is the unit of charge.
AMMETER🔥
Ammeter is an instrument that is used for measuring current. Ammeters that can detect and measure small current are called milliameters. Galvanometers are ammeters that can detect and measure very small current.
SENSITIVITY OF AMMETER🔥
An ammeter is said to be sensitive if it can detect and measure a very small current or detect and measure current no matter how small the current may be.
CONNECTION OF AMMETER🔥
Ammeters are connected in series in a circuit so that the current the ammeters are to measure will flow through the ammeter themselves.
What is electric current?
CURRENT🔥
Electric current is the time rate of flow of electric charge along a conductor.
Current is produced when an electric charge flow from one point to another in a circuit.
The s.i .unit of current is ampere and the symbol is A. For current, I is used.```
🔥Given that the current that is generated in a circuit for 5½ minutes when a given quantity of electric charge flows through a conductor is 1.25 A, determine the charge.
Current I = 1.25 ampere, time t = 5½ minutes = 5½ * 60 seconds = 11/2 * 60 seconds = 11 * 30 seconds
Time = 330 seconds.
Formula: current I = Charge / time
Substitution: 1.25 = charge / 330
Make charge the subject of the formula: charge = 1.25 * 330
Charge Q = 412.5 Coulomb
Question 3
Calculate the time for which 3000 Coulomb of charge will generate 2.25 A of current in a circuit.
SOLUTION🔥
Data given in the question:
Charge Q = 3000 Coulomb, current I = 2.25 Amperes
Formula: current I = charge / time
Substitution: 2.25 = 3000 / time
Make time the subject of formula : time = 3000 / 2.25. Time = 1333.33 seconds
*FORMULA FOR CALCULATING CURRENT:*
Current I = Charge measured in Coulomb / time measured in seconds.
Current = charge / time
EXAMPLES🔥
*Calculate the current generated when 250 coulomb of charge flow in a circuit for 3½ minutes.
SOLUTION🔥
Data given in the question:
Charge = 250 Coulomb, time = 3½ minutes = 3½ * 60 seconds = 7/2 * 60 seconds = 210 seconds
Time = 210 seconds.
Formula: Current I = charge / time
Substitution: Current I = 250 Coulomb / 210 seconds
Current I = 1.2ampere
EXAMPLES🔥
📌calculate the work done by a cell of emf 12.5 volt if a charge of 250 Coulomb is maintained in the circuit.
SOLUTION🔥
Data given in the question:
Emf = 12.5 Volt, charge = 250 Coulomb, work = ?
Formula: emf = work ( w ) / charge( q )
Substitution: 12.5 = work / 250
Make work the subject of the formula: work = 12.5 * 250.
work = 3125 joules.
Example 2
🔥320 joules of work is done in electrical circuit. If the charge that flow in the circuit is 1200 Coulombs, determine the electromotive force of the cell in the circuit.
SOLUTION🔥
Data given in the question:
Work done = 250 Joules, Charge = 1200 Coulombs, electromotive force = ?
Formula: electromotive force = work done / charge
Substitution: emf = 250 / 1200 . emf = 0.208 volt.
The ammeter is an instrument for measuring current.
We also have millimeters
Millimeters measures smaller currents .
While very small current are detected by sensitive instrument called galvanometers
Note 🔥✍️
Invace you see some questions with the unit mA or ûA
1mA=10-³A
1û=10-^6A
Such low currents are common in transistor radios and electric calculators
Let's move to
ELECTRIC CURRENT 🔥✍️
Are you following?
ELECTRIC CIRCUIT🔥
Electric circuit is the Path through which electric current flows in a circuit. It consist of the source of electric energy connected through a conductor to a load and a switch.
TYPES OF ELECTRIC CIRCUITS🔥
Closed circuit.🔥
A closed circuit is a circuit that is in the on position. In a closed circuit, the current flows through an external resistor. The resistor can be a bulb or any alliance connected in the part of the current.
OPEN CIRCUIT🔥
An open circuit is a circuit that is in the off position. In an open circuit, the battery maintain no current in an external resistor and the bulb.
Short circuit🔥
A short circuit is a closed circuit that has no load connected to it.
What is potential different ?🔥✍️
POTENTIAL DIFFERENCE P.D🔥
For electric current to flow in a circuit, there must be a pressure difference between the two points in the electric field. This pressure difference is the potential difference.
DEFINITION OF POTENTIAL DIFFERENCE🔥
The potential difference between any two points in an electric field is the work that is done in moving a positive charge of one Coulomb from one point to another in an electric field.
It can also be defined as the electrical pressure difference between the two points in an electric field. Potential difference is measured in volt, (V).
ELECTROMOTIVE FORCE EMF🔥
Electromotive force is the total work done in driving one coulomb of electric charge round a circuit. Of can also be defined as the total energy per Coulomb obtained from a cell. The unit of emf is volt, V. Emf can also be defined as joule per Coulomb.
E=W/Q
E.m.f =work/charge
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