OHM'S LAW Flashcards
(26 cards)
What is CURRENT in electricity?
CURRENT (I) exists in a conductor whenever electric charge is being transferred from one point to another in that conductor.
What is the SI unit of current?
The SI unit of current is the coulomb per second (C/s), called the ampere, symbol A.
What is the formula for CURRENT?
I = Q/t, where I = CURRENT, Q = charge transferred, t = time taken to transfer this charge.
What is POTENTIAL DIFFERENCE (V)?
POTENTIAL DIFFERENCE between two points in a conductor is measured by the work required to transfer unit charge from one point to the other.
What is the definition of a volt?
A volt is the potential difference between two points in a conductor when 1 joule of work is required to transfer 1 coulomb of charge.
What is the formula for potential difference?
V (volts) = W (joules) / Q (coulombs).
What work is done by a charge in a circuit with potential difference?
If two points of an external circuit have a potential difference V, then a charge Q does work W = QV as it moves from the higher to the lower potential point.
What is ELECTROMOTIVE FORCE (ε)?
ELECTROMOTIVE FORCE is present when an agent such as a battery or generator does work on the charge moving through it, providing electrical energy.
How is emf measured?
Emf is measured by the potential difference between the terminals when the battery or generator is not delivering current.
What are the units of electromotive force?
The units of emf are the same as the units of potential difference, both measured by work per unit charge.
What is the SI unit of emf?
The SI unit of emf is the volt (1 joule per coulomb).
What is RESISTANCE (R)?
RESISTANCE of a conductor is the property that depends on its dimensions, materials, and temperature, determining the current produced by a given potential difference.
What is the formula for resistance?
R = V/I, where R = resistance, V = potential difference, I = current.
What is the SI unit of resistance?
The SI unit of resistance is the volt per ampere (V/A), called the ohm, symbol Ω.
What is the relationship between volts, ohms, and amperes?
V (volts) = R (ohms) × I (amperes).
What does Ohm’s Law state about electrical current in a metallic conductor?
The value of the steady electrical current I is proportional to the potential difference V between the ends of the conductor at a constant temperature.
What is the relationship between current (I), voltage (V), and resistance (R) according to Ohm’s Law?
Ohm’s Law states that V = IR, where the resistance (R) is constant at constant temperature.
How can Ohm’s Law be applied in a circuit?
Ohm’s Law can be applied to any part of a circuit or to the entire circuit.
What is the formula for total current in a circuit according to Ohm’s Law?
The total current (I) in a circuit is given by I = ε / R, where ε is the total electromotive force (emf) and R is the total resistance.
How is current measured in a circuit?
Current is measured by inserting a low resistance ammeter in series with the circuit.
How is potential difference measured in a circuit?
Potential difference is measured by connecting a high resistance voltmeter across the resistance being measured, in parallel.
How is resistance calculated using an ammeter and voltmeter?
Resistance is computed by dividing the voltmeter reading by the ammeter reading, according to R = V / I.
What is the terminal voltage of a battery or generator when delivering current?
Terminal voltage = emf - voltage drop in internal resistance = ε - Ir.
