Current Electricity Flashcards
What is the difference between electromotive force (emf), potential difference (p.d.), current, and internal resistance of a cell?
Emf: The total energy provided by a cell or battery per coulomb of charge.
Potential Difference (p.d.): The energy difference between two points in a circuit.
Current: The flow of electric charge through a conductor, measured in amperes (A).
Internal Resistance: The resistance within the cell that causes some energy to be lost as heat.
What is Ohmβs law?
Ohmβs law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance of the conductor.
How do you calculate the effective total resistance of resistors in series and parallel?
Series: The total resistance
π
_π‘ππ‘ππ
is the sum of all resistances
π
_π‘ππ‘ππ = π
β + π
β + β― + π
β
Parallel: The reciprocal of the total resistance π
_π‘ππ‘ππ
is the sum of the reciprocals of each resistance
1/π
_π‘ππ‘ππ = 1/π
β + 1/π
β + β― + 1/π
_β
What is the potentiometer and how is it used to measure emf, current, and internal resistance?
A potentiometer is a device used to measure the emf of a cell, the internal resistance, and current without drawing any current from the circuit. It does this by comparing the unknown emf with a known voltage.
What are the advantages of using a potentiometer over a voltmeter?
A potentiometer provides more accurate measurements because it doesnβt draw current from the circuit, thus avoiding the error of βlost volts.β
It can measure very small potential differences with high precision.
How is Kirchhoffβs law applied in electrical networks?
Kirchhoffβs Current Law (KCL): The total current entering a junction equals the total current leaving the junction.
Kirchhoffβs Voltage Law (KVL): The sum of all electromotive forces and potential differences around any closed loop in a circuit equals zero. These laws are used to analyze complex electrical circuits and determine the current and voltage in each component.
How can you determine the resistivity and conductivity of a conductor?
Resistivity π = π
π΄ / πΏ
where π
is the resistance,
π΄ is the cross-sectional area, and
πΏ is the length of the conductor. Conductivity is the inverse of resistivity,
π = 1 / π
What is the formula for Ohmβs Law?
Ohmβs Law is given by the formula π = πΌπ
where: π is the voltage across the conductor (in volts),
πΌ is the current through the conductor (in amperes),
π
is the resistance of the conductor (in ohms).
What is the formula for the power of an electrical circuit?
The power π in an electrical circuit is given by the formula:
π = πΌπ where:
π is the power (in watts),
πΌ is the current (in amperes),
π is the voltage (in volts).
Alternatively, using Ohmβs Law:
* π = πΌΒ² Γ π
* π = πΒ² / π
β
How do you calculate the energy stored in a capacitor?
The energy πΈ stored in a capacitor is given by the formula:
πΈ = 1 / 2 πΆπΒ²
where:
* πΆ is the capacitance (in farads),
* π is the voltage across the capacitor (in volts).
Q: How do you calculate the electromotive force (emf) in a circuit with internal resistance?
The emf π of a cell is related to the terminal voltage π, current πΌ, and internal resistance π by:
π = π + πΌπ
What is the formula for calculating the potential difference using a potentiometer?
The potential difference
π measured using a potentiometer is given by:
π = π Γ π
where: π is the potential gradient,
π is the length of the wire.
What are Kirchhoffβs Laws and their formulas?
Kirchhoffβs Current Law (KCL): The sum of currents entering a junction equals the sum of currents leaving the junction:
β πΌ_in = β πΌ_out
Kirchhoffβs Voltage Law (KVL): The sum of all electromotive forces and potential differences in any closed loop of a circuit equals zero:
β π = 0
