Electric Field Strength

• What is an electric field?

  A region where a charge experiences a force
• How is electric field strength defined?

  Force per unit charge on a test charge
• What is the formula for electric field strength?

  E = F / Q
• What does E represent in the equation E = F / Q?

  Electric field strength (N C$^{-1}$)
• What does F represent in the equation E = F / Q?

  Electric force on the charge (N)
• What does Q represent in the equation E = F / Q?

  Magnitude of the charge (C)
• Why is a positive test charge used in defining electric field strength?

  It sets a convention for field direction
• In an electric field, which direction does a positive charge experience force?

  In the direction of the field
• In an electric field, which direction does a negative charge experience force?

  Opposite to the direction of the field
• What type of quantity is electric field strength?

  A vector quantity
• How is electric field strength directed in relation to charges?

  Away from positive charges, towards negative charges
• If a charged particle experiences a force of 0.3 N and the electric field strength is $3.5 \times 10^4 \text{ N C}^{-1}$, how do you calculate the charge?


  Use Q = F / E
• What is the charge on a particle if the force is 0.3 N and electric field strength is $3.5 \times 10^4 \text{ N C}^{-1}$?


  $8.6 \times 10^{-6} \text{ C}$
• What are the steps to calculate the charge from electric field strength and force?

  1. Write down the equation: E = F / Q
  2. Rearrange for charge: Q = F / E
  3. Substitute values and calculate
• What are the characteristics of electric field strength?

  • Defined as force per unit charge
  • Calculated using E = F / Q
  • Direction is away from positive charges and towards negative charges
  • A vector quantity