Edexcel IGCSE Physics 复习笔记 2.1.2 Voltage & Energy

• The terminals of a cell make one end of the circuit positive and the other negative
• This sets up a potential difference across the circuit
  • This is sometimes known as the voltage

   

• Potential difference is defined as:

The amount of energy transferred per unit of charge passing through the terminals

• This means that one volt (the unit of potential difference) is equivalent to one joule (the unit of energy) per coulomb (the unit of charge):

1 V = 1 J / C

• The equation linking the energy transferred, voltage and charge is given below:

• Where:
  • V = potential difference, measured in volts (V)
  • E = energy transferred, measured in joules (J)
  • Q = charge moved, measured in coulombs (C)

   

• This can be rearranged using the formula triangle below:

Step 1: List the known quantities

• • Voltage, V = 6 V
  • Charge, Q = 4200 C

   

Step 2: State the equation linking potential difference, energy and charge

• • The equation linking potential difference, energy and charge is:

   

E = V × Q

Step 3: Substitute the known values and calculate the energy transferred

E = 6 × 4200

E = 25 200 J

• • Therefore, 25 200 J of energy is transferred in the lamp