Define electric potential at a point.

The work done per unit charge in taking a small positive test charge from infinity to that point. It is a scalar quantity, measured in J C -1 or V, with a sign matching the charge producing it.

State how electric potential varies with distance for a positive point charge and for a negative point charge.

Positive charge: potential is positive and decreases as distance increases Negative charge: potential is negative and increases (towards zero) as distance increases

Is electric potential a scalar or vector quantity, and how does this affect combining the potentials due to multiple point charges?

Electric potential is a scalar quantity, so the combined potential at a point due to multiple charges is found by simple algebraic addition (not vector addition).

How does electric potential vary inside and outside a uniformly charged conducting sphere?

Constant inside the sphere, then decreases with distance outside the sphere.

The electric potential due to a point charge is .......... proportional to the distance from the charge.

The electric potential due to a point charge is inversely proportional to the distance from the charge.

True or False? The electric potential due to a point charge follows the same sign convention as gravitational potential, which is always negative.

False. Unlike gravitational potential, which is always negative, the sign of electric potential corresponds to the sign of the charge producing it — positive for a positive charge, negative for a negative charge.

Define the potential gradient of an electric field.

The rate of change of electric potential with respect to displacement in the direction of the field.

On a graph of electric potential V against distance r from a point charge, what does the gradient at a given point represent?

The electric field strength E at that point.

How can the potential difference Δ V between two points be determined from a graph of electric field strength E against distance r ?

Δ V is equal to the area under the graph between those two points.

As the distance from a point charge increases, the magnitude of the potential gradient .......... .

As the distance from a point charge increases, the magnitude of the potential gradient decreases .

True or False? The V - r graph for a point charge is steeper than the corresponding E - r graph.

False. The V - r graph (1/ r relation) is shallower than the E - r graph (1/ r 2 relation).

Under what circumstances is work done as a charge moves through an electric field?

A positive charge moves against the field lines A negative charge moves with the field lines

State when work is done ON an electric field, and when work is done BY an electric field, as the separation of two charges changes.

On the field: bringing similar charges together, or separating opposite charges By the field: separating similar charges, or bringing opposite charges together

The electric potential energy of two point charges is .......... at infinite separation.

The electric potential energy of two point charges is zero at infinite separation.

True or False? The electric potential energy of a system of two point charges can only ever be positive.

False. Electric potential energy can be positive or negative , depending on the signs of the two charges — like charges give a positive E p , opposite charges give a negative E p .

A LevelPhysicsCambridge (CIE)Flashcards18. Electric FieldsElectric Potential

Electric Potential (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontElectric Potential
Define electric potential at a point.
FrontElectric Potential
State how electric potential varies with distance for a positive point charge and for a negative point charge.
BackElectric Potential
Positive charge: potential is positive and decreases as distance increases
Negative charge: potential is negative and increases (towards zero) as distance increases

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Cards in this collection (20)

Define electric potential at a point.
The work done per unit charge in taking a small positive test charge from infinity to that point. It is a scalar quantity, measured in J C^-1 or V, with a sign matching the charge producing it.
What is the value of electric potential at infinity?
Zero.
State how electric potential varies with distance for a positive point charge and for a negative point charge.
- Positive charge: potential is positive and decreases as distance increases
- Negative charge: potential is negative and increases (towards zero) as distance increases
Is electric potential a scalar or vector quantity, and how does this affect combining the potentials due to multiple point charges?
Electric potential is a scalar quantity, so the combined potential at a point due to multiple charges is found by simple algebraic addition (not vector addition).
How does electric potential vary inside and outside a uniformly charged conducting sphere?
Constant inside the sphere, then decreases with distance outside the sphere.
The electric potential due to a point charge is .......... proportional to the distance from the charge.
The electric potential due to a point charge is inversely proportional to the distance from the charge.
True or False?
The electric potential due to a point charge follows the same sign convention as gravitational potential, which is always negative.
False.
Unlike gravitational potential, which is always negative, the sign of electric potential corresponds to the sign of the charge producing it — positive for a positive charge, negative for a negative charge.
Define the potential gradient of an electric field.
The rate of change of electric potential with respect to displacement in the direction of the field.
Write the equation relating electric field strength E to the potential gradient, and explain the meaning of the negative sign.
$E = - \frac{Δ V}{Δ r}$
The negative sign shows that the potential gradient acts in the opposite direction to the field strength and electric force.
On a graph of electric potential V against distance r from a point charge, what does the gradient at a given point represent?
The electric field strength E at that point.
How can the potential difference ΔV between two points be determined from a graph of electric field strength E against distance r?
ΔV is equal to the area under the graph between those two points.
As the distance from a point charge increases, the magnitude of the potential gradient ...........
As the distance from a point charge increases, the magnitude of the potential gradient decreases.
True or False?
The V-r graph for a point charge is steeper than the corresponding E-r graph.
False.
The V-r graph (1/r relation) is shallower than the E-r graph (1/r² relation).
Define the electric potential energy of two point charges.
$E_{p} = \frac{Q_{1} Q_{2}}{4 π ϵ_{0} r}$
The energy stored due to the relative positions of two charges; E_p = 0 at infinite separation.
Under what circumstances is work done as a charge moves through an electric field?
- A positive charge moves against the field lines
- A negative charge moves with the field lines
Write the equation for the work done in moving a charge q through a potential difference ΔV.
$Δ W = q Δ V$
State when work is done ON an electric field, and when work is done BY an electric field, as the separation of two charges changes.
- On the field: bringing similar charges together, or separating opposite charges
- By the field: separating similar charges, or bringing opposite charges together
Write the equation for the change in electric potential energy ΔE_p when a charge q moves from a distance r₁ to r₂ from a charge Q.
$Δ E_{p} = q Δ V = \frac{Q q}{4 π ϵ_{0}} (\frac{1}{r_{2}} - \frac{1}{r_{1}})$
The electric potential energy of two point charges is .......... at infinite separation.
The electric potential energy of two point charges is zero at infinite separation.
True or False?
The electric potential energy of a system of two point charges can only ever be positive.
False.
Electric potential energy can be positive or negative, depending on the signs of the two charges — like charges give a positive E_p, opposite charges give a negative E_p.

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