An electric field is the region of space in which electric charges at rest experience an electrostatic force.
(a)
(b) Fig 15.16: Electric fields of different shapes An electric field is represented on a diagram by lines called electric field lines (lines of force).
Electric Field Lines ELECTRIC FIELD LINES
An electric field line is the line along which a positive charge would move if placed in the electric field.
The electric field line gives the vector direction for the electric field.Where the electric field is strong, the field lines are close together; where the field is weak, the lines are far apart.
DEMONSTRATION 15.5 Demonstration of an Electric Field Pattern Apparatus
Oil and semolina, large container, high voltage d.c. power supply, metal plates, leads
Procedure Set up apparatus as illustrated in Fig 15.17. Sprinkle semolina on the oil between the plates. Turn on the high voltage d.c. power supply.
Observation and Conclusion The semolina will form parallel lines between the plates showing the electric field pattern.
Container Metal plate
(c)
(d)
(e)
High voltage d.c. power supply
Semolina Metal plate Cooking oil
Note Different field patterns can be shown by using different-shaped or charged electrodes as shown in Fig 15.18.
