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WorksheetsP.3.7.3.2 Electric field strength
Total questions: 46
Worksheet time: 23mins
A conducting sphere holding a charge of +10 μC is placed centrally inside a second uncharged conducting sphere.
Which diagram shows the electric field lines for the system?
A charged spherical conductor has a radius r. An electric field of strength E exists at the surface due to the charge. What is the potential of the spherical conductor?
r2 E
r E2
E/r
r E
Two parallel metal plates of separation a carry equal and opposite charges. Which graph best represents how the electric field strength E varies with the distance x in the space between the two plates?
An electron moves through a distance of 0.10 m parallel to the field lines of a uniform electric field of strength 2.0 kN C–1. What is the work done on the electron?
zero
1.6 × 10–17 J
3.2 × 10–17 J
1.6 × 10–21 J
A parallel-plate capacitor is fully charged and then disconnected from the power supply. A dielectric is then inserted between the plates. Which row correctly identifies the charge on the plates and the electric field strength between the plates?
Charge: Stays the same
Electric field strength: Increases
Charge: Increases
Electric field strength: Decreases
Charge: Increases
Electric field strength: Increases
Charge: Stays the same
Electric field strength: Decreases
An electron on the surface of the Earth is placed in an electric field of strength 5000 N C−1. What is the ratio shown for the electron?
1.1 × 10−14
2.9 × 10−10
3.4 × 109
9.0 × 1013
An electron moving with constant speed enters a uniform electric field at right angles to the direction of the field. What is true about the force acting on the electron?
It is at right angles to the direction of the field.
It is in the opposite direction to the direction of the field.
It causes the electron to continue in the same direction with its speed increasing steadily.
It causes the electron to continue in the same direction with its speed decreasing steadily.
Two fixed parallel metal plates P and Q are at constant electrical potentials of +100 V and +70 V respectively. A proton travelling from P to Q experiences a force F due to the electric field between P and Q, and a change of potential energy of ΔEp.
Which line, A to B, in the table gives the direction of F and the value of ΔEp?
Direction of F: towards P
ΔEp: +30 eV
Direction of F: towards Q
ΔEp: +30 eV
Direction of F: towards Q
ΔEp: -30 eV
Direction of F: towards P
ΔEp: -30 eV
The diagram shows a small negative charge at a point in an electric field, which is represented by the arrowed field lines. Which of the following statements, about what happens when the charge is displaced, is correct?
When the negative charge is displaced
to the left the magnitude of the electric force on it decreases.
to the right its potential energy increases.
along the line PQ towards Q its potential energy decreases.
along the line PQ towards P the magnitude of the electric force on it is unchanged.
Two parallel metal plates are separated by a distance d and have a potential difference V across them. Which expression gives the magnitude of the electrostatic force acting on a charge Q placed midway between the plates?
The electric potential at a distance r from a positive point charge is 45 V. The potential increases to 50 V when the distance from the point charge decreases by 1.5 m. What is the value of r?
1.3m
1.5m
7.9m
15m
Which of the following statements about a parallel plate capacitor is incorrect?
The capacitance of the capacitor is the amount of charge stored by the capacitor when the pd across the plates is 1 V.
A uniform electric field exists between the plates of the capacitor.
The charge stored on the capacitor is inversely proportional to the pd across the plates.
The energy stored when the capacitor is fully charged is proportional to the square of the pd across the plates.
The diagram shows a charge –Q being moved from point X to point Y between two charged parallel plates separated by a distance d. Which one of the following graphs best illustrates how the magnitude of force F on the charge varies with distance as it moves towards Y?
The diagram shows four point charges, each +Q, at the corners of a square of side 2a. What is the electric field strength at P, the centre of the square?
zero
A satellite orbiting the Earth moves to an orbit which is closer to the Earth. Which line shows correctly what happens to the speed of the satellite and to the time it takes for one orbit of the Earth?
Speed of satellite: decreases
Time For One Orbit Of Earth: decreases
Speed of satellite: decreases
Time For One Orbit Of Earth: increases
Speed of satellite: increases
Time For One Orbit Of Earth: decreases
Speed of satellite: increases
Time For One Orbit Of Earth: increases
A positive ion has a charge−to−mass ratio of 2.40 × 107 C kg–1. It is held stationary in a vertical electric field. Which line, A to D, in the table shows correctly both the strength and the direction of the electric field?
A
B
C
D
In the equation X = (ab)/rn , X represents a physical variable in an electric or a gravitational field, a is a constant, b is either mass or charge and n is a number.
Which line, A to D, in the table provides a consistent representation of X, a and b according to the value of n?
The symbols E, g, V and r have their usual meanings.
A
B
C
D
Which one of the following statements is correct?
An electron follows a circular path when it is moving at right angles to
a uniform magnetic field.
a uniform electric field.
uniform electric and magnetic fields which are perpendicular.
uniform electric and magnetic fields which are in opposite directions.
Which one of the following statements is correct?
The force between two charged particles
is always attractive
can be measured in C2 F–1 m–1
is directly proportional to the distance between them
is independent of the magnitude of the charges
Which one of the following statements is correct?
When a negative ion is projected into an electric field
the field can change the magnitude of the velocity but not its direction
the field can change the direction of the velocity but not its magnitude
the field can change both the magnitude and the direction of the velocity
the ion will accelerate in the direction of the field
Two fixed parallel metal plates X and Y are at constant potentials of + 100 V and + 70 V respectively. An electron travelling from X to Y experiences a change of potential energy ΔEp.
Which line, A to D, in the table shows correctly the direction of the electrostatic force F on the electron and the value of ΔEp?
A
B
C
D
Two horizontal parallel plate conductors are separated by a distance of 5.0 mm in air. The lower plate is earthed and the potential of the upper plate is +50 V. Which line, A to D, in the table gives correctly the electric field strength, E, and the potential, V, at a point midway between the plates?
A
B
C
D
Which path, A to D, shows how an electron moves in the uniform electric field represented in the diagram?
A
B
C
D
The diagram shows a negative ion at a point in an electric field, which is represented by the arrowed field lines. Which one of the following statements correctly describes what happens when the ion is displaced? When the negative ion is displaced
to the left the magnitude of the electric force on it decreases.
to the right its potential energy increases.
along the line PQ towards Q its potential energy decreases.
along the line PQ towards P the magnitude of the electric force on it is unchanged.
Which one of the following statements about a parallel plate capacitor is incorrect?
The capacitance of the capacitor is the amount of charge stored by the capacitor when the pd across the plates is 1V.
A uniform electric field exists between the plates of the capacitor.
The charge stored on the capacitor is inversely proportional to the pd across the plates.
The energy stored when the capacitor is fully charged is proportional to the square of the pd across the plates.
Which line correctly describes the trajectory of charged particles which enter separately, at right angles, a uniform electric field, and a uniform magnetic field?
uniform electric field: parabolic
uniform magnetic field: circular
uniform electric field: circular
uniform magnetic field: parabolic
uniform electric field: circular
uniform magnetic field: circular
uniform electric field: parabolic
uniform magnetic field: parabolic
The distance between two point charges of + 8.0 nC and + 2.0 nC is 60 mm. At a point between the charges, on the line joining them, the resultant electric field strength is zero. How far is this point from the + 8.0 nC charge?
20 mm
25 mm
40 mm
45 mm
Which one of the following cannot be used as a unit for electric field strength?
J m–1 C–1
J A–1 s–1m–1
N A–1 s–1
J C m–1
An ion carrying a charge of +4.8 × 10–19C travels horizontally at a speed of 8.0 × 105ms–1. It enters a uniform vertical electric field of strength 4200 V m–1, which is directed downwards and acts over a horizontal distance of 0.16m. Which one of the following statements is not correct?
The ion passes through the field in 2.0 × 10–7s.
The force on the ion acts vertically downwards at all points in the field.
The magnitude of the force exerted on the ion by the field is 1.6 × 10–9 N.
The horizontal component of the velocity of the ion is unaffected by the electric field.
What is the acceleration of an electron at a point in an electric field where the field strength is 1.5 × 105 V m–1?
1.2 × 106 m s–2
1.4 × 1013 m s–2
2.7 × 1015 m s–2
2.6 × 1016 m s–2
Which one of the following statements about a charged particle in an electric field is correct?
No work is done when a charged particle moves along a field line.
No force acts on a charged particle when it moves along a field line.
No work is done when a charged particle moves along a line of constant potential.
No force acts on a charged particle when it moves along a line of constant potential.
Two parallel metal plates separated by a distance d have a potential difference V across them.What is the magnitude of the electrostatic force acting on a charge Q placed midway between the plates?
Which one of the following statements about electric field strength and electric potential is incorrect?
Electric potential is a scalar quantity.
Electric field strength is a vector quantity.
Electric potential is zero whenever the electric field strength is zero.
The potential gradient is proportional to the electric field strength.
Two parallel metal plates separated by a distance d have a potential difference V across them. What is the magnitude of the electrostatic force acting on a charge Q placed midway between the plates?
An electron travelling at constant speed enters a uniform electric field at right angles to the field. While the electron is in the field it accelerates in a direction which is
in the same direction as the electric field.
in the opposite direction to the electric field.
in the same direction as the motion of the electron.
in the opposite direction to the motion of the electron.
The electrical field strength, E, and the electrical potential, V, at the surface of a sphere of radius r carrying a charge Q are given by the equations shown
A school van de Graaff generator has a dome of radius 100 mm. Charge begins to leak into the air from the dome when the electric field strength at its surface is approximately 3 × 106 V m–1.
What, approximately, is the maximum potential to which the dome can be raised without leakage?
3 × 104 V
3 × 105 V
3 × 106 V
3 × 107 V
Which line, A to D, correctly describes the trajectory of charged particles which enter, at right angles, (a) a uniform electric field, and (b) a uniform magnetic field?
A
B
C
D
Two parallel metal plates of separation a carry equal and opposite charges. Which one of the following graphs, A to D, best represents how the electric field strength E varies with the distance x in the space between the plates?
Two horizontal parallel plate conductors are separated by a distance of 5.0 mm in air. The lower plate is earthed and the potential of the upper plate is + 50 V. Which line, A to D, gives correctly the electric field strength, E, and the potential, V, at a point midway between the plates?
A
B
C
D
The diagram shows how the electric potential varies along a line XX’ in an electric field. What will be the electric field strength at a point P on XX’ which is mid−way between R and S?
5.0 V m−1
10 V m−1
20 V m−1
30 V m−1
If the potential difference between a pair of identical, parallel, conducting plates is known, what is the only additional knowledge required to determine the electric field strength between the plates?
the permittivity of the medium between the plates
the separation and area of the plates
the separation and area of the plates and the permittivity of the medium between the plates
the separation of the plates
Which one of the following statements about electric field strength and electric potential is incorrect?
Electric potential is a scalar quantity.
Electric field strength is a vector quantity.
Electric potential is zero whenever the electric field strength is zero.
The potential gradient is proportional to the electric field strength.
Which one of the following statements about electric potential and electric field strength is correct?
Electric potential is zero whenever the electric field strength is zero.
Electric field strength is a scalar quantity.
Electric potential is a vector quantity.
Electric potential due to a point charge varies as 1/r where r is the distance from the point charge.
Which one of the following arrangements of charge will produce zero electric field strength and zero electric potential at the point labelled P?
An electric field is maintained in the region between two circular parallel metal plates, the separation of which is small compared with their diameter. Along the line X to Y between the plates
the electric field strength decreases uniformly
the electric field strength increases uniformly
the electric field strength increases and then decreases again
the electric field strength is the same everywhere
Four point charges W, X, Y and Z are each placed at a distance a from O as shown in the diagram. X, Y and Z each have a charge –Q and W has a charge +Q. The resultant electric field strength at O is
