Electric fields

• What does Coulomb's Law describe?

  The electric force between two charges
• How does the electric field affect charged particles?

  It exerts a force on nearby charged particles
• What is the relationship defined by Coulomb's Law?

  Force is proportional to charge product and inversely to distance squared

  
• How can the electric force between two charges be calculated?

  Using the formula $F =$$\frac{Q_1 Q_2}{4 \pi \epsilon_0 r^2}$
• What does $F$ represent in Coulomb's Law?


  Electrostatic force between two charges
• What does $Q_1$ and $Q_2$ represent in the formula?


  Magnitudes of the charges
• What does $r$ represent in Coulomb's Law?


  Distance between the centres of the charges
• What does a higher permittivity indicate?

  More resistance to creating an electric field
• What is the Coulomb constant $k$?


  $k =$$\frac{1}{4 \pi \epsilon_0}$
• How do electric forces differ from gravitational forces?

  Electric forces can be attractive or repulsive
• What happens when two like charges interact?

  They experience repulsion
• What happens when two opposite charges interact?

  They experience attraction
• How do you calculate the electric force between an alpha particle and a gold nucleus?

  Use Coulomb's law with their charges and distance
• What is the charge of an alpha particle?

  $2e$
• What is the charge of a gold nucleus?

  $79e$
• How do you calculate the electric force using Coulomb's law?

  Substitute charges and distance into the formula

  
• What is the electric field strength formula?

  $E =$$\frac{F}{Q}$

  
• What does electric field strength indicate?

  Force per unit charge at a point

  
• How does a positive test charge behave in an electric field?

  It experiences a force in the direction of the field

  
• How does a negative test charge behave in an electric field?

  It experiences a force opposite to the direction of the field

  
• What is the formula for electric field strength between parallel plates?

  $E =$$\frac{V}{d}$

  
• What happens to electric field strength with increased voltage?

  It increases with greater voltage
• What happens to electric field strength with increased separation between plates?

  It decreases with greater separation
• How do you calculate the electric force on a charge between parallel plates?

  Use $F =$$E \times Q$

  
• What is the relationship between electric field lines and charge type?

  Lines point away from positive and towards negative

  
• How do electric field lines behave in a uniform electric field?

  They are equally spaced and parallel

  
• What happens to electric field strength with distance from a point charge?

  It decreases with increasing distance

  
• How do electric field lines behave around a charged conducting sphere?

  They are similar to those around a point charge

  
• What is the effect of bringing two opposite charges closer together?

  The attractive force between them increases

  
• What is the effect of bringing two like charges closer together?

  The repulsive force between them increases
• What is the neutral point between two like charges?

  Where the resultant electric force is zero

  
• How does the electric field behave between two parallel plates?

  It is uniform between the plates

  
• What happens to the electric field beyond the edges of parallel plates?

  It becomes non-uniform
• How do electric field lines behave between two parallel plates?

  They are directed from positive to negative plate

  
• How does the electric field behave around a point charge traveling between two parallel plates?

  It combines both fields around the charge and plates

  
• What should you always label on electric field line diagrams?

  The arrows on the field lines
• What is the significance of the direction of electric field lines?

  They indicate the direction of force on a positive charge

  
• What happens to electric field lines when they touch the surface of a charge?

  They must touch the surface and cannot cross
• How do electric field lines behave around a point mass?

  They are only directed towards the mass
• What is the difference between electric and gravitational field lines?

  Electric forces can be attractive or repulsive