Radial Electric Field

• What happens to the strength of an electric field due to a point charge as distance increases?

  It decreases with the square of the distance

  
• What type of law describes the strength of an electric field due to a point charge?

  Inverse square law
• What is the equation for electric field strength due to a point charge?

  E = $\frac{F}{q} =$$\frac{Q}{4\pi\epsilon_0r^2}$

  
• What does Q represent in the electric field strength equation?

  The point charge producing the field

  
• What does r represent in the electric field strength equation?

  Distance from the center of the charge

  
• What does ε represent in the electric field strength equation?

  Permittivity of free space

  
• How does electric field strength behave in a radial electric field?

  It is not constant and follows an inverse square law
• What is the electric field strength inside a charged sphere?

  It is zero

  
• How does electric field strength behave outside a charged sphere?

  It decreases with distance according to an inverse square law

  
• What are electric force and field strength classified as?

  Vector quantities
• What direction does the electric field strength point for a negative charge?

  Towards the center of the charge
• What direction does the electric field strength point for a positive charge?

  Away from the center of the charge

  
• How do you find the electric force or field strength at a point due to multiple charges?

  By vector addition of each field
• What is the resultant field for charges along the same line?

  It is the vector addition of the fields
• How do you calculate the resultant field if two fields are in opposite directions?

  By taking the difference between the fields
• What factors determine the direction of the resultant electric field?

  The types and magnitudes of the charges
• How can the resultant electric field be determined for a point making a right-angled triangle with the charges?

  Using Pythagoras theorem
• What should you remember when combining electric fields from multiple charges?

  The direction corresponds to the signs of the charges
• What does the direction of the electric force or field indicate for a positive charge?

  It points away from the positive charge
• What does the direction of the electric force or field indicate for a negative charge?

  It points towards the negative charge