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18. Electric fields
A section of Physics, 9702
Listing 10 of 195 questions
Define electric field strength. Two parallel metal plates in a vacuum are separated by a distance of 15 mm, as shown in . metal plate metal plate 15 mm particle mass 1.7 × 10–27 kg charge +1.6 × 10–19 C + – A B A uniform electric field is produced between the plates by applying a potential difference between them. A particle of mass 1.7 × 10–27 kg and charge +1.6 × 10–19 C is initially at rest at point A on one plate. The particle is moved by the electric field to point B on the other plate. The particle reaches point B with kinetic energy 2.4 × 10–16 J. Calculate the speed of the particle at point B. speed = m s–1 State the work done by the electric field to move the particle from A to B. work done = J Use your answer in to determine the force on the particle. force = N Determine the potential difference between the plates. potential difference = V On , sketch a graph to show the variation of the kinetic energy of the particle with the distance x from point A along the line AB. Numerical values for the kinetic energy are not required. kinetic energy x / mm
9702_w17_qp_21
THEORY
2017
Paper 2, Variant 1
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Define electric potential at a point. State the relationship between electric potential and electric field strength at a point. Two parallel metal plates A and B are situated a distance 1.2 cm apart in a vacuum, as shown in . 1.2 cm –75 V plate B plate A helium nucleus x 0 V Plate A is earthed and plate B is at a potential of –75 V. A helium nucleus is situated between the plates, a distance x from plate A. Initially, the helium nucleus is at rest on plate A where x = 0. The helium nucleus is free to move between the plates. By considering energy changes of the helium nucleus, explain why the speed at which it reaches plate B is independent of the separation of the plates. As the helium nucleus (4 2He) moves from plate A towards plate B, its distance x from plate A increases. Calculate the speed of the nucleus after it has moved a distance x = 0.40 cm from plate A. speed = m s–1
9702_w18_qp_41
THEORY
2018
Paper 4, Variant 1
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Define electric potential at a point. State the relationship between electric potential and electric field strength at a point. Two parallel metal plates A and B are situated a distance 1.2 cm apart in a vacuum, as shown in . 1.2 cm –75 V plate B plate A helium nucleus x 0 V Plate A is earthed and plate B is at a potential of –75 V. A helium nucleus is situated between the plates, a distance x from plate A. Initially, the helium nucleus is at rest on plate A where x = 0. The helium nucleus is free to move between the plates. By considering energy changes of the helium nucleus, explain why the speed at which it reaches plate B is independent of the separation of the plates. As the helium nucleus (4 2He) moves from plate A towards plate B, its distance x from plate A increases. Calculate the speed of the nucleus after it has moved a distance x = 0.40 cm from plate A. speed = m s–1
9702_w18_qp_43
THEORY
2018
Paper 4, Variant 3
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A constant potential difference is applied between two horizontal metal plates. A charged oil droplet is held stationary by the electric field between the plates. horizontal metal plates charged oil droplet As some of the oil evaporates, the droplet loses mass and starts to accelerate. Its charge remains constant. In which direction does the droplet accelerate, and which change needs to be made to the separation of the plates in order to stop this acceleration?
9702_w20_qp_13
MCQ
2020
Paper 1, Variant 3
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Questions Discovered
195