resistors Flashcards
What is an ohmic resistor?
A resistor whose resistance remains constant when the current changes
The current through an ohmic resistor is directly proportional to the potential difference across it, provided the temperature remains constant.
Describe the relationship between current and potential difference in an ohmic resistor.
Current is directly proportional to potential difference
If the potential difference doubles, the current also doubles, assuming constant temperature.
What type of graph represents the relationship of an ohmic resistor?
A straight line graph crossing through zero with current on the y-axis and potential difference on the x-axis
This linear relationship indicates constant resistance.
How does the resistance of filament lamps change with temperature?
The resistance increases as the temperature increases
As current flows, the filament heats up, increasing its resistance and reducing current flow at higher temperatures.
What is the shape of the graph representing the resistance of a diode?
An S-shaped curve with the middle crossing through zero
The diode allows current to flow in one direction and has higher resistance in the reverse direction.
What is the function of a thermometer in a circuit?
It changes its resistance with temperature
At low temperatures, resistance increases, while at high temperatures, resistance decreases.
What is a thermistor?
A resistor that changes resistance with temperature
Thermistors can be used in circuits as temperature sensors or thermostats.
What is an LDR?
A light-dependent resistor
Its resistance depends on light intensity, being high in low light and low in bright light.
How does light intensity affect the resistance of an LDR?
Resistance is high at low light intensity and low at high light intensity
LDRs can be used in circuits to automatically turn on lights at night.
How can resistance be calculated?
Resistance = Potential difference / Current
Example: If potential difference is 10V and current is 5A, resistance = 10V / 5A = 2 ohms.
What is the correct connection for measuring potential difference across a component?
Use a voltmeter connected in parallel with the component
This allows accurate measurement of the potential difference across the component.
What is the correct connection for measuring current through a component?
Use an ammeter connected in series with the component
This setup allows the ammeter to measure the current flowing through the component.
True or False: The resistance of a diode is constant.
False
The resistance of a diode varies depending on the direction of current flow.
All notes
some resistors are ohmic resistance the resistance of an ohmic doesn’t change when the current changes the current income conductor is directly proportional to potential difference across to resistor. This means that if the potential difference across resistance doubles current will also double however this is only true if the temperature is constant if this was shown on a graph with current and the y axis and potential difference on the x axis it would be a straight line crossing through zero
The resistance of some components does change with current
The resistance of some components does change with correct for example in filament lamps and tires when a current flows through filament the heat up. This is because some of the energy is transferred into the energy store filament as a potential what’s the filament increases? Its temperature also increase distance increases with temperature. This means that potential difference across the famine increases its resistance auto increases as a result a lower current flows through the filament at higher temperatures. The resistance of a diode depends on the traction of a current if this was shown in the graph with current on the y access and potential difference on the X access it would be a S shape with the middle of the S crossing through zero
The current diet can only flow in One Direction because they have a higher resistance in the reverse direction.
The resistance of thermometers and LDR depend on the surroundings
A thermometer is a resistor that changes his resistance with temperature
Low temperatures, the resistance increases
High temperatures the resistance goes down
this means is themistors can be used in circuits as temperature sensors or thermostats
An LDR is a light dependent resistor
The resistance of an LDR depends on the light intensity
In low levels of light (low light intensity) resistance is hig
In high levels of light (brighter light) the resistance is low
This means LDR could be used in circuits to automatically turn on lights at night
Resistance can be found using potential difference and current
We can measure the resistance of a component by using its current potential difference.
Potential difference of component with a meter meter should be connected in parallel with the component its measuring.
The current component can be measured with an ammeter
An amateur is connected in series with the component it is measuring
Remember resistance is potential difference divided by home
Potential difference / current = 10V/5A
=2 ohms
The component has a resistance of two ohms
