Chapter – 7

Electricity and circuit

Planning an investigation

Identify the variables

Independent variable – the variable that is altered during a scientific experiment.

Dependent variable – the variable being tested or measured during a scientific experiment.

Controlled variable – a variable that is kept the same during a scientific experiment. Any change in a controlled variable would invalidate the results.

Example

Practical 1.4 - Investigating the effect of temperature on the action of an enzyme

• Independent variable – temperature.
• Dependent variable – time taken for starch to be digested.
• Controlled variables – pH, enzyme concentration and volume of enzyme.

Contents

• Circuit basics
• Circuit basics
• Potential Deference and Resistance
• Investigating components
• Circuit device
• Investigating LDRs and thermistors
• Warm –up and exam questions
• Series circuits
• Parallel circuits
• Investigating circuits

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2

Contents

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• Warm –up and exam questions
• Energy in circuits
• Heating in circuits and power rating
• Power in circuits
• Warm –up and exam questions
• Electricity in the home
• Electrical safety
• Warm –up and exam questions
• Revision summary for section -7

3

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