AQA OCR Edexcel A Level Physics Electric Fields Answers

1. Total for Question 1: 13 (a) Define the electric field strength at a point in space. [1] (b) State one similarity and one difference between the electric fields produced by charges and the gravitational fields produced by masses. [2] (c) Which two of the following statements are true? i. The direction of an electric field is that in which a negative charge would move. ii. Electric field lines are always perpendicular to the surface of a conductor. iii. The spacing of electric field lines is directly proportional to the field’s strength. iv. The direction of an electric field is that in which a positive charge would move. [2] (d) Sketch the electric fields produced by the following: i. A negative point charge. [1] ii. A positively charged sphere. [1] iii. Two parallel plates with opposite charges. [2] iv. Two spheres with opposite charges. [2] v. A positively charged sphere and a negatively charged plate. [2] 2. A metal sphere has a radius, r, of 1.0 m and a positive charge of 5.0 × 10−7 C. Total for Question 2: 9 (a) Calculate the electric field strength at a distance, d, of 1.0 m from the surface of the sphere. [3] (b) Without repeating the full calculations you performed in the previous part, determine how the calculated field strength would change in the following circumstances. i. The charge doubles. [1] ii. r triples. [2] iii. d is five times larger. [3] 3. An electron is accelerated from rest by a uniform electric field. Given that the field strength is 1.2 105 NC−1, calculate the following: (a) The force experienced by the electron. Total for Question 3: 8 [2] (b) Its speed after 4 ns. [3] (c) Its displacement after 8 ns. [3]