Unit 2 Current, potential diff & resistance Flashcards
What source must the circuit have in order for electrical charge to flow through a closed circuit?
a source of potential difference
What is electric current?
the flow of electrical charges
What is the rate of flow of electrical charge?
the size of electric current
In a single closed loop does the current at different points change?
No, stays the same
relationship between current, resistance and potential diff
The greater the resistance of the component the smaller the current for a given potential difference across the component.
potential difference equation
pd= current x resistance
what is the relationship between current and the potential difference across a resistor at a constant temp?
directly proportional, the resistance remains constant as the current changes
What is the resistance like of components like lamps, diodes and thermistors
It changes with the current through the component.
what is a thermistor?
What happens in hot and cold conditions?
-A temperature dependent resistor
- In hot conditions, low resistance
- In cold conditions, high resistance.
what is a use of a thermistor?
temp detectors. e.g car engine sensors and electronic thermostats.
resistance of LDR when light intensity increases and decreases.
As light intensity increases, resistance of LDR decreases.
As light intenisty decreases, resistance of LDR increases.
One application of LDR in circuits
Switching lights on when it gets dark is required.
Components connected in series:
- same current through each component
- Total potential difference of the power supply is shared between the components.
- total resistance of two components is the sum of the resistance of each component.
Components connected in parallel:
- potential diff across each component is the same
