2.01, 2.04, 2.05, 2.07-2.21 Fundamentals of circuits

What is the formula between power, current and voltage

Power = current x voltage

Formula between energy transferred, current, voltage and time

Energy transferred = current x voltage x time

Cell

Battery

Switch

Fixed resistor

What does a resistor do

Limits or resists the current flow

Variable resistor

Lamp

Ammeter

Voltmeter

Fuse

What does a fuse do

It is a wire that melts when a high current flows through it, breaking the circuit so that it prevents electrical damage or injury

Motor

Diode

LED

Light Dependent Resistor (LDR)

Thermistor

Heater

Generator

Power supply (AC) Alternating Current

What way does flow charge?

From positive to negative

What is current?

The rate of flow of charge (electrons) through a circuit per second

What does an ammeter do

Measures current

Describe the current in a series circuit

The current in the same anywhere in the circuit

Where can you connect an ammeter on a series circuit

Anywhere

Describe the current in a parallel circuit

The current splits at the junction and the current of each branch equals the current from the power source

Advantages of parallel circuit

If one branch of the series breaks the others are still intact and work, all bulbs will end up the same brightness and brighter

What is voltage

Amount of energy per unit charge

Where to put a voltmeter

Across a component

Explain the voltage in a series circuit

It is shared equally amongst each component

Explain the voltage in a parallel circuit

Voltage is the same across every branch of the parallel circuit

What is resistance

It is how hard it is to produce a big current in a circuit.

What is ohms law?

Voltage = current x resistance

How to draw diode in circuit

The arrow points to the negative side from the positive side

What does an IV graph measure?

Current (y axis) against voltage (x axis)

What does a linear line mean on an IV graph?

The resistance is constant

Components with a linear IV graph

Fixed resistor (at constant temp), wires (at constant temp)

Components with a non linear IV graph

Filament lamps, diodes, LDRs, thermistors

What component is this IV graph for

Diode

What component is this IV graph for

Lamp

Why does the resistance of the lamp increase as the current of the lamp increase

Higher current causes higher temperature, causing atoms to vibrate more, causing increase in resistance as it becomes more difficult for free electrons to pass through, causing more resistance

Describe relationship between voltage and current in lamp

As the voltage increases, the current increases but at a proportionately slower rate

How can you read resistance on an IV graph

The flatter the slope, the higher the resistance

Describe the relationship between resistance and light intensity in an LDR

As the resistance increases, the light intensity decreases

Describe the relationship between the resistance and temp in a thermistor

As resistance increases, temp decreases

Formula with energy, charge and voltage

Energy = charge x voltage

Formula with power, energy, time

Power = energy/time