Chapter 19: Electric Potential and Capacitors

What is electric potential energy?

The energy stored due to the position of a charge in an electric field.

What does electric potential (V) represent?

Electric potential energy per unit charge, measured in volts (V).

What is the SI unit of electric potential?

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

What is an electron-volt (eV)?

The energy gained by an electron accelerating through a potential difference of 1 V, equal to 1.602 × 10^-19 J.

How does a 1.5 V battery function?

It provides 1.5 J of energy per Coulomb of charge through a circuit.

What is the relationship between electric potential difference (ΔV) and electric field (E) in a uniform field?

ΔV = -E·d, where d is the distance between two points.

What is the formula for electric potential due to a point charge?

V = k * (Q/r), where k ≈ 8.99 × 10^9 N·m²/C².

What does the term 'equipotential surface' mean?

A surface where every point has the same electric potential, requiring zero work to move a charge along it.

What is capacitance (C)?

The ability of a system to store charge per unit potential difference, defined as C = Q/V.

What happens to capacitance when a dielectric is inserted?

Capacitance increases due to the reduction of the electric field.

What is the formula for energy stored in a capacitor?

U_C = 1/2 CV², where C is capacitance and V is the potential difference.

What is the difference between capacitors in series and parallel?

In series, charge is the same and voltages add; in parallel, voltages are the same and charges add.

What is the energy density of electric fields?

Energy stored per unit volume in an electric field, given by U_E = (1/2)ε₀E².

What is the significance of equipotential lines?

They indicate regions of constant electric potential and are always perpendicular to electric field lines.

How do you calculate the net electric potential from multiple point charges?

By summing the individual potentials: V_total = Σ(k * q_i/r_i).

What is the role of capacitors in defibrillators?

They store electrical energy and release it rapidly to restore heart rhythm.

What is the relationship between electric field strength (E) and potential difference (ΔV)?

E = ΔV/d, where d is the distance over which the potential difference occurs.

What is the formula for calculating the equivalent capacitance of capacitors in series?

1/C_eq = 1/C₁ + 1/C₂ + ... for all capacitors in series.

What is the formula for calculating the equivalent capacitance of capacitors in parallel?

C_eq = C₁ + C₂ + ... for all capacitors in parallel.

What is the effect of distance on electric potential in a uniform electric field?

Electric potential decreases linearly with distance in a uniform electric field.

How does the electric field relate to equipotential surfaces?

Electric field lines are always perpendicular to equipotential surfaces.

What is the significance of the constant k in the point charge potential formula?

It is Coulomb's constant, which quantifies the strength of the electric force between charges.

What happens to the energy stored in a capacitor if the voltage is doubled?

The energy stored increases by a factor of four, since U_C = 1/2 CV².

What is the relationship between charge (Q), capacitance (C), and voltage (V)?

Q = CV, indicating that charge is directly proportional to both capacitance and voltage.

What is the purpose of capacitors in computer keyboards?

They act as variable parallel-plate capacitors under each key to detect key presses.