A point charge (or charged sphere) creates a radial field - field lines spread outward
Electric Fields - OCR A-Level Physics
- A point chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). (or charged sphere) creates a radial fieldAn electric field whose lines diverge radially from (or converge towards) a point charge or charged sphere. - field lines spread outward (positive) or inward (negative) in all directions.
- The field strength decreases with the square of the distance from the chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).: it follows an inverse-square lawA relationship in which a physical quantity is inversely proportional to the square of the distance from its source..
- For a positive chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C)., E acts radially outward. For a negative charge, E acts radially inward.
$$E = \frac{Q}{4\pi\epsilon_0 r^2}$$
- This equation is obtained by combining Coulomb's lawThe electrostatic force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. F = $\frac{Q_1 Q_2}{4\pi\epsilon_0 r^2}$ with E = F/Q - the test charge Q_2 cancels.
- A graph of E against r gives a curve; a graph of E against 1/\(r^{2}\) gives a straight line through the origin with gradient $\frac{Q}{4\pi\epsilon_0}$.