IGCSEScienceEdexcelScience (Double Award)PhysicsRevision Notes2. ElectricityElectrical Power & Mains ElectricityCalculating Energy Transfers

Calculating Energy Transfers (Edexcel IGCSE Science (Double Award)): Revision Note

Exam code: 4SD0

Katie M

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Katie M

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Edexcel Science (Double Award): PhysicsEdexcel Physics

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Calculating energy transfers

  • Work is done when charge flows through a circuit

    • Work done is equal to the energy transferred

  • The amount of energy transferred by electrical work in a component (or appliance) depends upon:

    • The current, I

    • The potential difference, V

    • The amount of time the component is used for, t

  • When charge flows through a resistor, for example, the energy transferred is what makes the resistor hot

  • The energy transferred can be calculated using the equation:

E space equals space P space cross times space t

  • Where:

    • E = energy transferred in joules (J)

    • P = power in watts (W)

    • t = time in seconds (s)

E space equals space I space cross times space V space cross times space t

  • Where:

    • I = current in amperes (A)

    • V = potential difference in volts (V)

  • When charge flows around a circuit for a given time, the energy supplied by the battery is equal to the energy transferred to all the components in the circuit

  • You can read more about how energy is transferred in our revision note, Energy Stores & Transfers

Worked Example

Calculate the energy transferred in 1 minute when a current of 0.7 A passes through a potential difference of 4 V.

 

Answer:

Step 1: Write down the known quantities

  • Time, t = 1 minute = 60 s

  • Current, I = 0.7 A

  • Potential difference, V = 4 V

Step 2: Write down the relevant equation

E space equals space I space cross times space V space cross times space t

Step 3: Substitute in the values

E space equals space 0.7 space cross times space 4 space cross times space 60

E space equals space 168 space straight J

Examiner Tips and Tricks

'Energy transferred' and 'work done' are often used interchangeably in equations, don't panic, they mean the same thing! Always remember that the time t in the above equations must always be converted into seconds.

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Katie M

Author: Katie M

Expertise: Physics Content Creator

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

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