3-Electrical Circuits Flashcards
If you rubbed a Perspex rod with a cloth what would happen?
The Perspex rod would lose electrons and become positively charged and the cloth would gain electrons and become negatively charged.
How does static build up?
When electrons (which have a negative charge) are ‘rubbed off’ on material onto another. The material receiving the electrons becomes negatively charged and the material giving the electrons becomes positively charged.
What would happen if you rubbed an ebonite rid with fur?
The ebonite rod would gain electrons and become negatively charged and the fur would lose electrons and become positively charged.
How to two objects of the same charge interact?
They repel one another.
How do two objects of opposite charges interact?
The attract each other.
What are substances that allow electrical charge to flow easily through them called?
Conductors.
What is potential difference (voltage)?
How much work is done per coulomb of charge that flows through a component.
What does a good conductor have?
A large number of free electrons so has low resistance. A component with high resistance resists the flow of these electrons.
What happens to the resistance as the temperature increases?
The ions in the metal vibrate faster and get in the way of the electrons. This increases resistance.
What is potential difference measured in?
Volts (V) using a voltmeter connected in parallel across the component.
What is current measured in?
Amperes (A) using an ammeter connected in series.
What is resistance?
A measure of how hard it is to get a current through a component at a particular potential difference.
How are resistors described on graphs?
As long as the temperature stays constant, the current through the resistor is directly proportional across the resistor.
How are filament lamps described on a graph?
As the temperature of the filament increases and the bulb gets brighter then the resistance of the lamp increases.
How are diodes described on a graph?
A diode allows a current to flow through it in one direction only. Has a very high resistance in the reverse direction so no current flows.
