Physics - Electric Fields
Flashcards
2022-03-01
What is electric field strength?
The force per unit positive charge.
What is the formula for electric field strength, $E$?
What is confusing about $E$ in electric field equations?
It represents electric field strength, not energy.
What are the units of electric field strength?
Newtons per Coulomb, $NC^{-1}$
What assumption are you making for point charges?
That the charge of a sphere can be considered to act from a central point.
In what direction do electric field lines get drawn?
From positive to negative.
What’s true about the field lines on an electric field diagram and a gravitational field diagram?
Electric field lines point outwards, gravitational field lines point inwards.
What are equipotentials?
A region in space where every point in it has equation electric potential energy.
How are equipotentials like contour lines on a map?
You don’t go up or down following contour lines.
What is Coulomb’s law for force $F$?
How does Coulomb’s law
\[F = \frac{Qq}{4\pi \epsilon _ 0 r^2}\]deal with different charges attracting or repelling one another?? $Qq$ being positive or negative depending on whether $q$ and $Q$ are negative or positive.
How does Coulomb’s law \(F = \frac{Qq}{4\pi \epsilon _ 0 r^2}\) deal with different charges attracting or repelling one another?
$Qq$ being positive or negative depending on whether $q$ and $Q$ are negative or positive.
What is the name for the constant $\epsilon _ 0$?
The permittivity of free space.
What is the formula for electric field strength $E$ using Coulomb’s law?
What is always true about electric field lines in relation to the conductor?
They are at right angles.
2022-03-02
What is always true about the position of equipotentials in relation to the electric field lines?
They are at right angles.
What type of electric field is Coulomb’s law
\[F = \frac{Qq}{4\pi \epsilon _ 0 r^2}\]relevant to?? Radial fields.
What are the two types of electric field under consideration in the electric fields topic?
- Radial fields
- Uniform fields
If
\[\frac{F}{Q} = \frac{v}{d}\]then what is a nice formula for electric field strength $E$??
\[E = \frac{v}{d}\]What type of electric field is Coulomb’s law \(F = \frac{Qq}{4\pi \epsilon _ 0 r^2}\) relevant to?
Radial fields.
If $\text{work done} = VQ$ but also $\text{work done} = Fd$, how can you come up with an equation for $\frac{F}{Q}$ (which is equivalent to $E$, electric field strength)?
If \(\frac{F}{Q} = \frac{v}{d}\) then what is a nice formula for electric field strength $E$?
2022-03-11
What is an alternative unit for electric field strength given that $E = \frac{v}{d}$?
How is an electron in a uniform field (such as the one constructed by two oppositely charged metal plates) like a projectile?
It experiences constant downward acceleration due to the electric field.
How could you work out the formula for the force on a charge in a uniform electric field given that $\frac{F}{Q} = \frac{V}{d}$?
What is electric potential?
The work done to bring a positive charge from infinity to a point.
What is electric potential at some imaginary point at infinity?
What is the formula for electric potential in terms of electric potential energy?
What is the formula for electric potential $V$ in terms of $Q$ and $r$?
What is the formula for capacitance $C$ in terms of charge stored $Q$ and potential difference $V$?
What are the units for capacitance, $C$?
How can you derive the formula for the capacitance of a sphere?
Substitute $V = \frac{Q}{4\pi\epsilon _ 0 r}$ into $C = \frac{Q}{V}$.