Electric Current, Voltage, Circuits, and Resistance Q&A flashcards

Flashcards based on lecture notes on current, voltage, electric shock, circuits, Ohm's Law, and resistance.

What is electric current (I) defined as?

The amount of charge (ΔQ) flowing through a wire per unit time (Δt), expressed as I = ΔQ/Δt.

What is the unit of electric current, and what is its equivalent in terms of Coulombs and seconds?

Ampere (A), where 1 A = 1 C/s.

What is voltage (U) defined as?

The energy (W) provided or used per unit of electric charge (Q), expressed as U = W/Q.

What is the unit of voltage, and what is its equivalent in terms of Joules and Coulombs?

Volt (V), where 1 V = 1 J/C.

How should an ammeter be connected in a circuit to measure current?

In series.

How should a voltmeter be connected in a circuit to measure voltage?

In parallel.

What is the effect of a current as low as 10 mA on the human body?

Muscle paralysis.

What is the potential effect of a current of 75+ mA on the human body?

Ventricular fibrillation.

What are the critical factors that determine the severity of an electric shock?

Current strength, duration of contact, path through body, and skin condition (dry vs. wet).

What are the initial steps to take if someone is experiencing an electric shock?

Cut power, do not touch the victim if still live, use a non-conductive object to separate the victim from the source, and check for breathing.

In a series circuit, what is the relationship between the total current and the current through each component?

The same current flows through all components; Itotal = I1 = I2 = …

In a series circuit, how is the total voltage related to the voltage across each component?

Voltage splits among components; Utotal = U1 + U2 + …

In a series circuit, how is the total resistance calculated?

Total resistance adds up; Rtotal = R1 + R2 + …

In a parallel circuit, what is the relationship between the voltage across each component?

All components share the same voltage; U = U1 = U2 = …

In a parallel circuit, how does the total current relate to the current in each branch?

Total current splits into branches; Itotal = I1 + I2 + …

In a parallel circuit, how is the total resistance calculated?

1/Rtotal = 1/R1 + 1/R2 + …

What is the key characteristic of a series circuit regarding the path of current?

One single path.

What is the main characteristic of a parallel circuit regarding the path of current?

Multiple paths.

State Ohm's Law.

U = R * I (Voltage = Resistance * Current), or R = U/I.

To what types of materials does Ohm's Law apply?

Ohmic materials (e.g., metals at constant temperature).

What is the formula relating resistance to resistivity, length, and cross-sectional area?

R = ρ * (L/A), where R is resistance, ρ is resistivity, L is length, and A is cross-sectional area.

How does increasing the length of a wire affect its resistance?

Longer wires have more resistance.

How does increasing the cross-sectional area of a wire affect its resistance?

Thicker wires have less resistance.

What formula is used to calculate the cross-sectional area of a circular wire?

A = πr², where r is the radius of the wire.

What does a higher resistance indicate about a component?

Less current flows for the same voltage.