LEARN IT 2: Electricity

Draw the circuit symbols for: switch open, switch closed, cell, battery, diode, resistor, variable resistor, LED (light emitting diode), lamp, fuse, voltmeter, ammeter, thermistor, LDR

What is current?

What must there also be in a closed circuit for electrical charge to flow?

What is another word for potential difference?

What is the formula that links charge, current and time?

What are the units for charge?

What two things affect the size of the current flowing in a circuit?

What is the formula that links potential difference, current and resistance?

What are the units for resistance?

What is resistance?

What is potential difference?

Where in a circuit should you always put an ammeter?

Where in a circuit should you always put a voltmeter?

What is an ohmic conductor? Give an example.

What is the mathematical relationship between current and voltage for an ohmic conductor?

What is a non-ohmic conductor? Give two examples

What is the difference between a linear and non-linear relation

What is the I-V (current-voltage) graph for a resistor?

Why is the I-V graph for a resistor that shape?

What is the mathematical relationship between I and V for the resistor graph? How do you know?

What is the I-V graph for a filament lamp?

Why is the I-V graph for a filament lamp that shape?

What is the I-V (current-voltage) graph for a diode?

Why is the I-V graph for a diode that shape?

How does the resistance of a thermistor change with temperature?

Sketch a resistance-temperature graph for a thermistor

What is a thermistor used for?

How does the resistance of an LDR change with light intensity?

Sketch a resistance-light intensity graph for an LDR

What is an LDR used for?

Sketch the circuit diagram used to find the resistance of a component (by measuring the current through it and the potential difference across it)

What happens if you remove a component in a series circuit?

What happens if you remove a component in a parallel circuit?

What is the rule for current in a series circuit?

How is the potential difference of the power supply given to components in a series circuit?

What would cause one component in a series circuit to get a bigger share of the potential difference from the supply?

How could you find the total resistance of components in series?

What is the rule for current in a parallel circuit?

How is the potential difference of the power supply given to components in a parallel circuit?

What would cause one component in a parallel circuit to get a bigger share of the current?

What is the total resistance of two resistance in a parallel circuit always less than?

In the UK, the mains supply has a frequency of 50Hz. What does this mean?

What is direct current (DC)? Give an example of something that provides DC?

What is alternating current (AC)? Give an example of something that provides AC?

List the names and colours of the wires inside a 3-pin plug

Why are the wires in a plug made of copper?

Why are the cables and the plug covered in plastic or rubber?

How are the live and neutral wires connected to an appliance?

What is the potential difference between the live wire and the earth wire?

What is the potential difference between the live wire and the neutral wire?

Why is there still a danger of electric shock from a plug/light switch even if it is switched off?

What is the job of the earth wire?

How do the earth wire and fuse work together to protect the user?

When charge flows through a resistor, what energy store is the energy transferred into?

When charge flows through a kettle, what energy store is the energy transferred into?

What does work done mean?

What two things affect the amount of energy transferred by an electrical appliance?

What is the formula that links energy transferred, power and time

What are the two formulae that link power, potential difference, current and resistance?

If an appliance has a high power rating, what does this mean?

What is the National Grid?

What is a step-up transformer?

What is a step-down transformer?

Explain why step-up transformers are used in the national grid

Explain why step-down transformers are used in the National Grid

Describe how to carry out a practical to investigate how the length of a wire affects its resistance

Describe how to carry out a practical to investigate the resistance of resistors in series and parallel

Describe how to carry out a practical to find the I-V (current-voltage) characteristics of a component, e.g. a filament lamp, diode or resistor

Symbols, names and units for equations