Electrical Field Practice
1.This question is about forces on charged particles in electric and magnetic fields.
The diagram shows two parallel plates situated in a vacuum. One plate is at a positive potential with respect to the other.
A positively charged particle passes into the region between the plates. Initially, the particle is travelling parallel to the plates.
(a)On the diagram,
(i)draw lines to represent the electric field between the plates.
(3)
(ii)show the path of the charged particle as it passes between, and beyond, the plates.
(2)
(b)An electron is accelerated from rest in a vacuum through a potential difference of 750 V.
(i)Determine the change in electric potential energy of the electron.
(ii)Deduce that the final speed of the electron is 1.6 × 107 m s–1.
......
......
......
(2)
2.A positively charged sphere falls vertically in a vacuum between two long parallel plates carrying opposite charges. Which one of the following diagrams best shows the path followed by the sphere?
(1)
3.This question is about forces on charged particles.
(a)A charged particle is situated in a field of force. Deduce the nature of the force-field (magnetic, electric or gravitational) when the force on the particle
(i)is along the direction of the field regardless of its charge and velocity;
(ii)is independent of the velocity of the particle but depends on its charge;
(iii)depends on the velocity of the particle and its charge.
(5)
(b)An electron is accelerated from rest in a vacuum through a potential difference of 2.1 kV. Deduce that the final speed of the electron is 2.7 × 107m s–1.
(3)
The electron in (b) then enters a region of uniform electric field between two conducting horizontal metal plates as shown below.
The electric field outside the region of the plates may be assumed to be zero. The potential difference between the plates is 95 V and their separation is 2.2 cm.
As the electron enters the region of the electric field, it is travelling parallel to the plates.
(c)(i)On the diagram above, draw an arrow at P to show the direction of the force due to the electric field acting on the electron.
(1)
Calculate the force on the electron due to the electric field.
(3)
(d)The plates in the diagram above are of length 12 cm. Determine
(i)the time of flight between the plates.
(1)
(ii)the vertical distance moved by the electron during its passage between the plates.
(3)
(e)Suggest why gravitational effects were not considered when calculating the deflection of the electron.
(2)
4.The diagram below shows lines of electric equipotential. The change in potential on moving from one line to the next is always the same. At which point does the electric field strength have its greatest magnitude?
(1)
5.The diagram below shows two lines of equipotential in a region of a uniform electric field. Line X has a potential of +50 V and line Y has a potential of +100V. The distance between X and Y is 2.0 cm.
Which one of the following correctly gives the direction of the electric field and its strength?
Direction / Strength / V cm–1A. / X Y / 25
B. / X Y / 100
C. / Y X / 25
D. / Y X / 100
(1)
6.Two isolated spheres X and Y of unknown materials are touching one another as shown below.
Sphere Y is negatively charged and sphere X is earthed. The earth connection is removed from sphere X and then the spheres are separated as shown below.
Sphere X is found to be positively charged and sphere Y remains negatively charged.
Which of the following describes the nature of the materials from which the spheres are made?
Sphere X / Sphere YA. / Insulator / Insulator
B. / Insulator / Conductor
C. / Conductor / Insulator
D. / Conductor / Conductor
(1)
7.The diagram below shows two parallel conducting plates that are oppositely charged.
The line XY is perpendicular to the plates.
Which of the following diagrams shows the variation along the line XY of the magnitude E of the electric field strength between the plates?
(1)
1