Electric Circuit Flashcards
(16 cards)
What are the components of an electric circuit?
- Wires
- Light bulbs
- Resistors
- Cells and batteries = Type of energy source
- Switches
- Ammeters and voltmeters
What is an electrical circuit?
A path where electrons travel to deliver their energy.
Draw an electric circuit using circuit symbols
Define voltage.
Voltage is the difference in charge between two points in a circuit.
Voltage is a measure of the amount of energy that is supplied to the charges by the voltage source (the supply voltage) and used by the charges as they pass through a component.
What is voltage measured in and how?
Volts (V) using a voltmeter.
What does a high and low voltage on the voltmeter mean?
The voltage is high if the electrons are supplied with a lot of energy or are losing lots of energy.
What is resistance and what is it measured in?
Resistance is a material’s tendency to resist the flow of charge (current).
Resistance is measured in ohms.
High resistance – difficult to flow
Low resistance – easy to flow
What factors affect the resistance of a conductor in a circuit?
The resistance depends on:
Material - metals have low resistance, rubber very high.
Length - Doubling the length is doubling the obstacles the electrons must pass through.
Thickness - Thin is harder to pass through than thick.
Define current (I) and what is it measured in?
Current is the rate at which charge is flowing.
The current is measured in amps. (amperes).
The current is measured using an ammeter.
Ammeters measure the amount of charge that flows through it every second.
State Ohm’s law.
V=IR
Voltage (V) = Current (I) x Resistance (R)
What is a series circuit and list the features?
In a series circuit, all the components are connected one after another to form a single loop.
- Voltage is shared equally across components.
- More components reduce the voltage shared.
- Switches turn all on/off.
- Current stops if one bulb blows - all bulbs go out.
What is a parallel circuit and list the features?
A parallel circuit has a number of branching circuits, each branch having its own components. (where components are connected across multiple paths.)
- Each branch can have a switch - can be turned off independently
- Only one branch is affected if bulb blows.
- Extra bulbs do not affect brightness. Each receives full supply of power.
What are the key differences between series and parallel circuits?
Current, voltage, path
Current: The same current flows throw all components in a series circuit. The total current is the sum of the currents flowing through each component in a parallel circuit.
Voltage: Voltage is shared equally across all components in series circuit. Each component in a parallel circuit have the same amount of voltage.
Path: A series circuit has a single path for current flow. Parallel circuit has multiple pathways or branches for current flow.
What are the key differences between series and parallel circuits? (Part 2)
Component failure, resistance
Component failure: In a series circuit, failure of one component breaks the entire circuit. Parallel circuit, failure of one component only affects that specific branch/path.
Resistance: Series circuit, total resistance increases as more components are added. Parallel circuit, total resistance decreases as more components are added.
Describe the proportional relationship between voltage, current, and resistance.
The proportional relationship between voltage, current, and resistance is described by Ohm’s Law:
Voltage = The curent multiplied by the resistance.
Voltage (V) = Current (I) x Resistance (R)
The voltage is directly proportional to current and resistance.
Provide examples of how changes in one variable affect the other variables.
- Voltage and Current
If resistance is constant, current increases when voltage increases. e.g Doubling the voltage across a resistor doubles the current. - Current and Resistance
If voltage is constant, current decreases when resistance increases. e.g If resistance doubles, current is cut in half. - Voltage and Resistance
If current is constant, voltage increases when resistance increases. e.g If resistance triples, voltage must triple to maintain the same current.
