Current Electricity

What is electric current?

Electric current is the rate of flow of electric charge past a point.

What is the SI unit of electric current?

The ampere (A), where 1 A = 1 coulomb per second.

What does the term "drift velocity" refer to?

Drift velocity is the average velocity of electrons in a conductor due to an electric field.

What factors affect drift velocity?

Drift velocity depends on the current, cross-sectional area, and electron density of the material.

How is a voltmeter connected in a circuit and why?

A voltmeter is connected in parallel with a device to measure its voltage. This configuration ensures that the voltmeter can measure the potential difference across the device without significantly altering the current flow.

How is an ammeter connected in a circuit and why?

A voltmeter is connected in parallel with a device to measure its voltage.An ammeter is connected in series to measure the current flowing through a circuit. This arrangement ensures that all the current passes through the ammeter for accurate measurement.

What is the law of conservation of current?

The current is the same at all points in a current-carrying wire; current in equals current out.

What is potential difference?

Potential difference is the energy per unit charge as charge moves between two points.

What is electromotive force (emf)?

Electromotive force (emf) is the total work done per unit charge when charge flows around a complete circuit.

What is resistance?

Resistance is a measure of how hard it is to push charges through a wire.

What does Ohm’s Law state?

Ohm’s Law states that current is directly proportional to voltage: I=V/RI = V/RI=V/R.

What distinguishes an ohmic material from a non-ohmic one?

An ohmic material obeys Ohm’s law (linear I–V relationship), while a non-ohmic material does not. An ohmic material has a constant resistance regardless of voltage or current, whereas a non-ohmic material has a varying resistance that can change with voltage or current.

What is resistivity?

Resistivity is a material-dependent constant that relates resistance to the material's length and cross-sectional area.It quantifies how strongly a material opposes the flow of electric current, expressed in ohm-meters (Ω·m).

What factors affect the resistivity of a material?

Resistivity is affected by purity, heat treatment, and temperature.

In a series circuit, what is true about current and resistance?

In a series circuit, resistors have the same current, and the total resistance is the sum of individual resistances.

In a parallel circuit, what is true about voltage and current?

In a parallel circuit, resistors have the same voltage, and the total current is the sum of the individual currents.

What is electrical power?

Power is the rate at which energy is transferred. Electrical power is calculated by the product of voltage and current.

What quantities affect the power dissipated in a component?

Power is related to the current through and the potential difference across the component. Constituent resistance and voltage across it.

What does Kirchhoff’s first law state?

Kirchhoff’s first law: the sum of currents entering a point equals the sum leaving; charge is conserved.

What does Kirchhoff’s second law state?

Kirchhoff’s second law: the sum of the emfs equals the sum of the potential differences in a closed loop; energy is conserved.

What is the purpose of a fuse in a household circuit?

A fuse prevents overheating by breaking the circuit if the current is too high.

What is alternating current (AC)?

AC is current that changes direction periodically.

What is direct current (DC)?

DC is current that flows in only one direction.

What device can measure frequency and voltage of AC?

An oscilloscope measures the frequency and voltage of an alternating current.

What does the root-mean-square (rms) value represent in AC?

The rms value is the steady current that delivers the same average power as the AC to a resistive load.