P4 Electric Circuits Flashcards
What is Current?
The rate of flow of charge
What equation links Current, Voltage and Resistance?
V = IR
What equation links Voltage, Energy and Charge?
E = QV
What is the rule for Current in a Series circuit?
It’s always the same and never used up
What is the equation linking Charge, Current and Time?
Q = IT
What’s the equation linking Power, Voltage and Current?
P = IV
What’s the equation linking Power, Current and Resistance?
P = RI^2
What equation links Power, Energy and Time?
P = E/T
What are the characteristics of an Ohmic conductor?
The current through it is directly proportional to the potential difference across it
What is the relationship between the total resistance of two resistors in parallel and the resistance of the smaller individual resistor
(+ Explain)
The total resistance is less than that of the smallest resistor, as there are now two pathways for current to flow. And by I = V/R, we can see that if the current is increasing, while the voltage is constant, the total resistance must be decreasing.
Explain how the resistance of a filament lamp changes as the potential difference across it increases
- Current increases when voltage increases
- Which causes the temperature of the filament to increase
- Atoms in the filament have more Ek and collide with
electrons more frequently - Causing resistance to increase
Describe the energy transfers when current flows through a resistor
When a resistor is connected to a battery, work is done to make electrons pass the resistor. Each electron repeatedly collides with the vibrating metal ions in the resistor, so the ions of the resistor gain kinetic energy and vibrate even more, and the resistor becomes hotter. The electrical work done by the battery is equal to the energy transferred to the resistor. Energy is transferred from a chemical store in the battery, to a thermal store in the resistor.
