Define an electric field .

An electric field is a region of space in which a charged particle experiences a force .

What happens when two charged particles have (a) like charges and (b) opposite charges?

Like charges (both positive or both negative) repel each other Opposite charges (positive and negative) attract each other

How does the electrostatic force between two charges change as their separation increases?

The force decreases as the separation between the charges increases.

True or False? A charged particle only experiences a force in an electric field if it is moving.

False. A charged particle experiences a force in an electric field whether it is stationary or moving . This is different from a magnetic field, where the charge must be moving to experience a force.

An electric field is a type of ..........

An electric field is a type of force field .

What name is given to the force exerted by one charged particle on another, due to its electric field?

This is called the electrostatic force .

Define electric field strength .

The force per unit charge acting on a positive test charge at that point.

In which direction does the electric field point relative to a positive charge and a negative charge?

Away from a positive charge Towards a negative charge

True or False? The equation E = F / Q cannot be used to find the field strength due to a negative charge.

False. The equation can still be used for a negative charge. Substituting a negative value for Q gives a negative value of E , showing that the field points in the opposite direction to that of a positive charge.

Electric field strength is a .......... quantity, since it has both magnitude and direction.

Electric field strength is a vector quantity, since it has both magnitude and direction.

Define Coulomb's law .

The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation.

What happens to the electrostatic force between two charges if the separation between them is doubled?

The force decreases to one quarter (¼) of its original value, since force follows an inverse square law with distance.

True or False? A negative value calculated for F E using Coulomb's law indicates a repulsive force between the two charges.

False. A negative F E indicates an attractive force (the charges are oppositely charged). A positive F E indicates a repulsive force (the charges are the same sign).

How is the charge on a uniform spherical conductor treated when applying Coulomb's law?

It can be treated as a point charge located at the centre of the sphere.

ε 0 is a physical constant that describes the capability of a .......... to permit electric fields.

ε 0 is a physical constant that describes the capability of a vacuum to permit electric fields.

Define a radial field .

A field produced by a point charge (or a charged sphere), in which the field lines point directly towards or away from the centre of the charge.

What happens to the electric field strength around a point charge if the distance from the charge is doubled?

The field strength decreases to one quarter (¼) of its original value, following an inverse square law with distance.

How does the direction of electric field lines around a point charge differ from gravitational field lines around a point mass?

Gravitational field lines always point towards the mass (gravity is always attractive) Electric field lines can point towards or away from the charge, depending on whether the charge is negative or positive

True or False? The electric field around a negative point charge points away from the charge.

False. The electric field around a negative charge points towards the centre of the charge. It only points away from a positive charge.

The area under a graph of electric field strength E against distance r represents the change in .......... .

The area under a graph of electric field strength E against distance r represents the change in electric potential .

Define electric potential .

The amount of work done per unit charge at that point.

Define the potential gradient at a point in an electric field.

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

How is the electric field strength at a point related to a graph of electric potential against distance?

The electric field strength at a point is equal to the gradient of the potential–distance graph at that point.

How does electric potential vary with distance from (a) a positive charge and (b) a negative charge?

Positive charge: V is positive and decreases with distance (1/ r relation) Negative charge: V is negative and increases with distance, i.e. becomes less negative (–1/ r relation)

True or False? Electric potential always decreases as distance from a charge increases, regardless of the charge's sign.

False. This is only true for a positive charge. For a negative charge, the potential is negative and increases (becomes less negative) with distance.

The electric potential energy of a positive test charge depends on the magnitude of its charge and the value of the .......... at that point.

The electric potential energy of a positive test charge depends on the magnitude of its charge and the value of the electric potential at that point.

Define a uniform electric field .

A field in which the electric field strength (and the force on a charge) is the same at every point, such as the field between two charged parallel plates.

What are the units of electric field strength between parallel plates, and what other unit are they equivalent to?

V m -1 , which is equivalent to N C -1 .

In which direction does the electric field point between two charged parallel plates?

From the plate connected to the positive terminal to the plate connected to the negative terminal.

True or False? The equation E = V / d can be used to find the electric field strength around a point charge.

False. E = V / d only applies to the uniform field between parallel plates. The field around a point charge is radial , so E = Q /(4π ε 0 r ²) must be used instead.

If one of the parallel plates is .......... , it has a potential of 0 V.

If one of the parallel plates is earthed , it has a potential of 0 V.

Define electric potential .

The work done per unit charge in bringing a positive test charge from infinity to that point

Why can electric potential be positive or negative, even though it is a scalar quantity?

Electric potential is positive around an isolated positive charge, since positive work is done bringing a positive test charge from infinity Electric potential is negative around an isolated negative charge, since negative work is done Electric potential is zero at infinity

The electric potential at a point is the work done per unit .......... in bringing a positive test charge from infinity to that point.

The electric potential at a point is the work done per unit charge in bringing a positive test charge from infinity to that point.

True or False? Electric potential is a vector quantity, so it has both magnitude and direction.

False. Electric potential is a scalar quantity — it has no direction. The positive or negative sign shows whether the potential is due to a positive or negative charge, not a direction

Define equipotential lines/surfaces .

Lines (2D) or surfaces (3D) that join together points of the same electric potential; always perpendicular to the electric field lines and drawn as dotted lines

In which direction do electric field lines always point, relative to positive and negative charges?

From the positive charge to the negative charge

State three properties of a uniform electric field, as shown by its field lines.

The field lines are equally spaced at all points The electric field strength is constant at all points in the field The force on a test charge has the same magnitude and direction at all points in the field

How does the electric field around a charged conducting sphere compare to the field around a point charge?

It is identical — the same as it would be if all the charge on the sphere were concentrated at its centre, so a charged sphere can be treated as a point charge in calculations

Equipotential lines for a radial field are concentric circles that become progressively further .......... with distance from the charge.

Equipotential lines for a radial field are concentric circles that become progressively further apart with distance from the charge.

True or False? Equipotential lines have arrows, just like field lines, to show the direction of increasing potential.

False. Equipotential lines are drawn as dotted lines with no arrows , since electric potential is a scalar with no direction, unlike the electric field which is a vector

International A Level (IAL)PhysicsEdexcelFlashcards4. Further Mechanics, Fields & ParticlesElectric Fields

Electric Fields (Edexcel International A Level (IAL) Physics): Flashcards

Exam code: YPH11

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FrontDefining an Electric Field
Define an electric field.
FrontDefining an Electric Field
What happens when two charged particles have (a) like charges and (b) opposite charges?
BackDefining an Electric Field
Like charges (both positive or both negative) repel each other
Opposite charges (positive and negative) attract each other

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Cards in this collection (48)

Define an electric field.
An electric field is a region of space in which a charged particle experiences a force.
What happens when two charged particles have (a) like charges and (b) opposite charges?
- Like charges (both positive or both negative) repel each other
- Opposite charges (positive and negative) attract each other
How does the electrostatic force between two charges change as their separation increases?
The force decreases as the separation between the charges increases.
True or False?
A charged particle only experiences a force in an electric field if it is moving.
False.
A charged particle experiences a force in an electric field whether it is stationary or moving. This is different from a magnetic field, where the charge must be moving to experience a force.
An electric field is a type of ..........
An electric field is a type of force field.
What name is given to the force exerted by one charged particle on another, due to its electric field?
This is called the electrostatic force.
Define electric field strength.
The force per unit charge acting on a positive test charge at that point.
State the equation linking electric field strength (E), force (F) and charge (Q).
$E = \frac{F}{Q}$
What are the SI units of electric field strength?
N C^-1
In which direction does the electric field point relative to a positive charge and a negative charge?
- Away from a positive charge
- Towards a negative charge
True or False?
The equation E = F/Q cannot be used to find the field strength due to a negative charge.
False.
The equation can still be used for a negative charge. Substituting a negative value for Q gives a negative value of E, showing that the field points in the opposite direction to that of a positive charge.
Electric field strength is a .......... quantity, since it has both magnitude and direction.
Electric field strength is a vector quantity, since it has both magnitude and direction.
Define Coulomb's law.
The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation.
State the equation for the electrostatic force, F_E, between two point charges (Coulomb's law).
$F_{E} = \frac{Q_{1} Q_{2}}{4 π ε_{0} r^{2}}$
What happens to the electrostatic force between two charges if the separation between them is doubled?
The force decreases to one quarter (¼) of its original value, since force follows an inverse square law with distance.
True or False?
A negative value calculated for F_E using Coulomb's law indicates a repulsive force between the two charges.
False.
A negative F_E indicates an attractive force (the charges are oppositely charged). A positive F_E indicates a repulsive force (the charges are the same sign).
How is the charge on a uniform spherical conductor treated when applying Coulomb's law?
It can be treated as a point charge located at the centre of the sphere.
ε₀ is a physical constant that describes the capability of a .......... to permit electric fields.
ε₀ is a physical constant that describes the capability of a vacuum to permit electric fields.
Define a radial field.
A field produced by a point charge (or a charged sphere), in which the field lines point directly towards or away from the centre of the charge.
State the equation for the electric field strength, E, at a distance r from a point charge Q.
$E = \frac{Q}{4 π ε_{0} r^{2}}$
What happens to the electric field strength around a point charge if the distance from the charge is doubled?
The field strength decreases to one quarter (¼) of its original value, following an inverse square law with distance.
How does the direction of electric field lines around a point charge differ from gravitational field lines around a point mass?
- Gravitational field lines always point towards the mass (gravity is always attractive)
- Electric field lines can point towards or away from the charge, depending on whether the charge is negative or positive
True or False?
The electric field around a negative point charge points away from the charge.
False.
The electric field around a negative charge points towards the centre of the charge. It only points away from a positive charge.
The area under a graph of electric field strength E against distance r represents the change in ...........
The area under a graph of electric field strength E against distance r represents the change in electric potential.
Define electric potential.
The amount of work done per unit charge at that point.
Define the potential gradient at a point in an electric field.
The rate of change of electric potential with respect to displacement in the direction of the field.
How is the electric field strength at a point related to a graph of electric potential against distance?
The electric field strength at a point is equal to the gradient of the potential–distance graph at that point.
How does electric potential vary with distance from (a) a positive charge and (b) a negative charge?
- Positive charge: V is positive and decreases with distance (1/r relation)
- Negative charge: V is negative and increases with distance, i.e. becomes less negative (–1/r relation)
True or False?
Electric potential always decreases as distance from a charge increases, regardless of the charge's sign.
False.
This is only true for a positive charge. For a negative charge, the potential is negative and increases (becomes less negative) with distance.
The electric potential energy of a positive test charge depends on the magnitude of its charge and the value of the .......... at that point.
The electric potential energy of a positive test charge depends on the magnitude of its charge and the value of the electric potential at that point.
Define a uniform electric field.
A field in which the electric field strength (and the force on a charge) is the same at every point, such as the field between two charged parallel plates.
State the equation for the electric field strength, E, between two parallel plates with potential difference V and separation d.
$E = \frac{V}{d}$
What are the units of electric field strength between parallel plates, and what other unit are they equivalent to?
V m^-1, which is equivalent to N C^-1.
In which direction does the electric field point between two charged parallel plates?
From the plate connected to the positive terminal to the plate connected to the negative terminal.
True or False?
The equation E = V/d can be used to find the electric field strength around a point charge.
False.
E = V/d only applies to the uniform field between parallel plates. The field around a point charge is radial, so E = Q/(4πε₀r²) must be used instead.
If one of the parallel plates is .........., it has a potential of 0 V.
If one of the parallel plates is earthed, it has a potential of 0 V.
Define electric potential.
The work done per unit charge in bringing a positive test charge from infinity to that point
Why can electric potential be positive or negative, even though it is a scalar quantity?
- Electric potential is positive around an isolated positive charge, since positive work is done bringing a positive test charge from infinity
- Electric potential is negative around an isolated negative charge, since negative work is done
- Electric potential is zero at infinity
State the equation for the electric potential V at distance r from a point charge Q.
$V = \frac{Q}{4 π ε_{0} r}$
where ε₀ is the permittivity of free space (F m^-1)
How does electric potential V vary with distance r from a point charge, and how does this compare with electric field strength E?
- Electric potential V is inversely proportional to distance: $V \propto \frac{1}{r}$
- Electric field strength E is inversely proportional to distance squared: $E \propto \frac{1}{r^{2}}$
The electric potential at a point is the work done per unit .......... in bringing a positive test charge from infinity to that point.
The electric potential at a point is the work done per unit charge in bringing a positive test charge from infinity to that point.
True or False?
Electric potential is a vector quantity, so it has both magnitude and direction.
False.
Electric potential is a scalar quantity — it has no direction. The positive or negative sign shows whether the potential is due to a positive or negative charge, not a direction
Define equipotential lines/surfaces.
Lines (2D) or surfaces (3D) that join together points of the same electric potential; always perpendicular to the electric field lines and drawn as dotted lines
In which direction do electric field lines always point, relative to positive and negative charges?
From the positive charge to the negative charge
State three properties of a uniform electric field, as shown by its field lines.
- The field lines are equally spaced at all points
- The electric field strength is constant at all points in the field
- The force on a test charge has the same magnitude and direction at all points in the field
How does the electric field around a charged conducting sphere compare to the field around a point charge?
It is identical — the same as it would be if all the charge on the sphere were concentrated at its centre, so a charged sphere can be treated as a point charge in calculations
Equipotential lines for a radial field are concentric circles that become progressively further .......... with distance from the charge.
Equipotential lines for a radial field are concentric circles that become progressively further apart with distance from the charge.
True or False?
Equipotential lines have arrows, just like field lines, to show the direction of increasing potential.
False.
Equipotential lines are drawn as dotted lines with no arrows, since electric potential is a scalar with no direction, unlike the electric field which is a vector

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