Phy2 - Electricity Flashcards
What is current?
The rate of flow of charge
What is the equation for charge flow?
Charge flow = current × time
Q = I × t
What is the equation for potential difference?
Potential Difference = current × resistance
V = I × R
For a given potential difference
what happens to the current when the resistance increases?
The current decreases
What happens to the resistance of a thermistor as temperature increases?
The resistance decreases
What happenes to the resistance of a LDR as light increases?
Resistance decreases
What is the diifference between direct current and alternating current?
• Direct current flows in only one direction
• Alternating current constantly changes direction
What is the rule for current in a series circuit?
Current stays the same througout the whole circuit
Name the electrical component in thermostats
Thermistor
Where are LDRs commonly found?
LDRs are used as automatic night
lights / burglar detectors (in bright light the resistance is low)
What is the National Grid?
A system of cables and transformers
What is the rule for potential difference in series circuits?
Potential difference is shared between components
Where should you place an ammeter to measure the current through a component?
The ammeter should be placed in series with the component
What is the rule for potential difference in a parallel circuit?
It stays the same in each branch
Where should you place a voltmeter to measure the potential difference through a component
The voltmeter should be placed parallel to the component
