Current Electricity Concepts

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Questions and Answers

Match the following terms with their corresponding formulas:

Ohm's Law = $V = IR$ Power in a resistor = $P = I^2R$ Resistance of a wire = $R = \rho L/A$ Drift Velocity = $I = n e A v$

Match the scenarios with the potential difference across a battery's terminals:

Battery is not connected in a circuit = $V = E$ Battery is supplying energy = $V = E - Ir$ Battery is short circuited = $V = 0$ Battery is being charged = $V = E + Ir$

Match the components with their current or voltage characteristics in series combination:

Current in series circuits = Same throughout Voltage in series circuits = Divided across resistors Equivalent resistance in series circuits = Sum of individual resistances Overall effect of series circuits = Increases effective resistance

Match the components with their current or voltage characteristics in parallel combination:

<p>Voltage in parallel circuits = Same across each branch Current in parallel circuits = Divided across branches Equivalent resistance in parallel circuits = Reciprocal of sum of reciprocals Overall effect of parallel circuits = Reduces effective resistance</p> Signup and view all the answers

Match the given formulas with what they represent in a potentiometer setup:

<p>Potential difference comparison = $V_{x}I_{x}= E_1I_1 / E_2I_2$ Internal resistance of cell = $r = R [ \sqrt{E_1/E_2} - 1]$ Unknown resistance in potentiometer = $R = Sl_x/(100 - l_x)$ Kirchhoff's Junction Rule = $\Sigma I = 0$</p> Signup and view all the answers

Flashcards

Ohm's Law

The potential difference (V) across a conductor is directly proportional to the current (I) flowing through it, with the constant of proportionality being the resistance (R). This relationship is represented by the equation V = I * R.

Electric Power

The power (P) dissipated by a resistor is the rate at which energy is transferred from the electrical circuit to the resistor. It can be calculated using the formulas P = I²R or P = V²/R, where I is the current, R is the resistance, and V is the voltage.

Resistors in Series

The combination of resistors in a circuit where the current flowing through each resistor is the same. The total resistance in a series circuit is the sum of the individual resistances. This means that the total resistance in a series circuit is always greater than the resistance of any individual resistor.

Resistors in Parallel

The combination of resistors in a circuit where the voltage across each resistor is the same. The reciprocal of the total resistance is equal to the sum of the reciprocals of the individual resistances. This means that the total resistance in a parallel circuit is always less than the resistance of any individual resistor.

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Potentiometer

A device used to measure an unknown resistance or to divide voltage. It uses a wire with a uniform resistance, and a sliding contact that can be moved along the wire to change the resistance. By comparing the voltage drops across different parts of the wire, we can determine the unknown resistance or voltage division.

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Study Notes

Current Electricity

Ohm's Law: V = IR (Voltage = Current × Resistance)
Electric Power: P = IV = I²R = V²/R (Power = Current × Voltage = Current² × Resistance = Voltage² / Resistance)
Potential Difference across a Battery: V = E – Ir (where E = electromotive force, I = current, r = internal resistance)
If the battery is supplying energy, V = E – Ir
If the battery is short circuited, V = 0
If the battery is being charged, V = E + Ir
Drift Speed: I = n e A v_d (Current = charge density × electron charge × cross-sectional area × drift velocity)
Resistance of a Wire: R = ρL/A (Resistance = resistivity × length / cross-sectional area)
Resistivity: ρ = m/n e²τA (Resistivity = mass/ (charge density × electron charge² × relaxation time × cross-sectional area))
Combination of Resistors:
Series: R_total = R₁ + R₂ + ...
Parallel: 1/R_total = 1/R₁ + 1/R₂ + ...
Potentiometer: Used to measure unknown voltage or EMF. V_x/E₂ = l₂ / l₁ (Voltage ratio equals length ratio)
Kirchhoff's Rules:
Junction Rule: Sum of currents entering a junction equals sum of currents leaving the junction (ΣI = 0).
Loop Rule: The sum of the voltages around any closed loop in a circuit is equal to zero (ΣV = 0).
Unknown Resistance: Using a known resistance and Kirchhoff's Laws, determine an unknown circuit resistance R = Sl / (100 - l) (where Sl represents the scale division and l the corresponding difference in reading)
Bulb Resistance: R α 1/P (Resistance is inversely proportional to Power)
In parallel, P = P₁ + P₂ (Power is the sum of individual power)
In series, 1/P = 1/P₁ + 1/P₂ (Power is the reciprocal of the sum of individual power)
R= V²/P (Resistance is equal to voltage squared divided by Power)
V, P are rated values for bulbs

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Description

Test your understanding of current electricity with this quiz covering fundamental principles such as Ohm's Law, electric power calculations, and resistance in circuits. Dive into the equations that govern electrical systems, including battery behavior and resistor combinations. Perfect for students learning the principles of electricity in physics.