Current and Charge Flashcards
What is the purpose of the cell?
A cell is necessary to push electrons around a complete circuit. A battery consists of two or more cells. The + symbol indicates the positive terminal of the cell.
What is the purpose of a switch?
A switch enables the current in a circuit to be switched on or off.
What is the purpose of an indicator?
An indicator, such as a bulb, is designed to emit light as a signal when current passes through it.
What is the purpose of a diode?
A diode allows the current through in one direction only.
What is the purpose of a fixed resistor?
A fixed resistor limits the current in a circuit.
What is the purpose of a variable resistor?
Allows the current to be varied.
What is the purpose of a fuse?
A fuse is designed to melt and therefore break the circuit if the current through is greater than a certain amount.
What is the purpose of a voltmeter?
A voltmeter is used to measure potential difference. (voltage)
What is the purpose of the ammeter?
The ammeter is used to measure electric current.
What is electric current?
The flow of charge through a circuit.
How do electric circuits work?
Metals contain electrons that are free to move randomly between the positively charged metal ions. When the switch is closed the battery the battery provides a push which males all of these electrons move in one direction at the same time. The electrons transfer energy as they interact with the metal ions in the filament of the bulb. This makes the filament hot so it radiates light.
Why is the current at any part of the circuit the same?
Because the number of electrons per second that pass through any part of the circuit is the same as any other part.
What is the formula for Charge flow?
Q ( charge flow) = I (amps) x t(time (seconds))
Why would you damage a portable radio if you put the batteries the wrong way round?
This is because the diode in a portable radio allows current through only when it is connected the right way.
Give the method for a circuit test?
- Connect a variable resistor in series with a bulb, an ammeter and a cell.
- Adjust the slider of the variable resistor. This alters the amount of current flowing through the bulb so it affects its brightness.
