Podcast
Questions and Answers
What does the symbol for a variable resistor include?
What does the symbol for a variable resistor include?
In a parallel circuit, the potential difference is different for each component.
In a parallel circuit, the potential difference is different for each component.
False (B)
What is the equation for current?
What is the equation for current?
Q = It
A thermister's resistance increases with ______.
A thermister's resistance increases with ______.
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What is the purpose of step-up transformers in the National Grid?
What is the purpose of step-up transformers in the National Grid?
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Match the types of wires used in homes to their functions:
Match the types of wires used in homes to their functions:
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Total resistance in a series circuit is the sum of the individual resistances.
Total resistance in a series circuit is the sum of the individual resistances.
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What average voltage is electricity delivered to homes?
What average voltage is electricity delivered to homes?
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Study Notes
Circuit Symbols
- There are 12 circuit symbols to learn
- The variable resistor has an arrow through it
- The thermister does not have an arrow
- The fuse has a straight line through it
- Arrows within circuit symbols represent light
Current
- Current is defined as the flow of electric charge
- The equation for current is Q=It where:
- Q = Charge (Coulombs)
- I = Current (Amps)
- t = Time (Seconds)
- Current flows through wires via electrons
- Imagine wires as roads, electrons as cars, and charge as passengers
Potential Difference/Voltage
- Voltage drives electrons through a circuit
- Imagine voltage as the engine of a car
Resistance
- The equation for resistance is V=IR where:
- V = Potential Difference (Volts)
- I = Current (Amps)
- R = Resistance (Ohms)
- Resistance can be affected by:
- Strength of components (like resistors)
- Filament lamps
- Length and diameter of wires
- Imagine resistance as traffic on a road
Light Dependent Resistor (LDR)
- An LDR's resistance is dependent on light intensity
- Higher light intensity = lower resistance
- Remember the graph of the relationship between light intensity and resistance to remember this rule
Thermister
- A thermister's resistance is dependent on temperature
- Higher temperature = lower resistance
- Remember the graph of the relationship between temperature and resistance to remember this rule
Series Circuits
- Components are connected in a single loop
- Total potential difference is the sum of all PDs in the circuit
- Current is the same everywhere in the circuit
- Total resistance is the sum of all resistances in the circuit
Parallel Circuits
- Components are connected in branches
- Potential difference is the same everywhere in the circuit
- Total current is the sum of all currents in the circuit
- Current splits at junctions
- In two resistors wired in parallel, total resistance is lower than the smallest resistor
Electricity in the Home
- Red Wire (Live): Carries the current
- Green and Yellow Wire (Earth): Grounds the electricity for safety
- Blue Wire (Neutral): Completes the circuit
- Power equation: P=IV where:
- P = Power (Watts)
- I = Current (Amps)
- V = Potential Difference (Volts)
The National Grid
- Power stations produce electricity
- The National Grid aims to deliver this electricity to homes
- Step-up transformers increase voltage in wires to reduce current:
- This reduces resistance
- Prevents overheating
- Reduces energy loss through thermal energy
- Step-down transformers reduce voltage to a safer level
- Electricity is delivered to homes at 230 volts on average.
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Description
This quiz covers essential concepts of electric circuits, including circuit symbols, current flow, voltage, and resistance. You'll learn how these principles apply to various components in a circuit. Test your knowledge on the key definitions and equations related to electric circuits.
