Electricity Flashcards
What is it called when electrons rub off one material, and are deposited on another?
Static electricity.
How is charge gained by static?
The process is called charging by friction, giving or taking electrons.
What does a charged object create?
An electric field.
What does the second charged object experience?
A non-contact force.
What happens at a greater distance between two objects?
The static force becomes weaker.
How can current be described using charge?
Current is the rate of flow of electric charge.
What happens to current in a series circuit?
It stays the same.
What does a diode do?
Allow current to only flow in one direction.
What is the name of a component where current is directly proportional to the potential difference? What is the law called?
An ohmic conductor. Ohms law.
What happens to a current-p.d graph when resistance is increased?
It becomes less steep.
What does the line look like for a filament lamp?
A curve in a wave-like shape.
What happens to the resistance of a filament lamp when current increases? Why?
It also increases because the resistance increases as its temperature increases.
What is resistance the same for, regardless of direction?
The same size current.
How does a diode allow current in one direction only?
Because the other direction has a very high resistance, making the current through it virtually zero.
When does an LED emit light?
When current passes through it in the forward direction.
How does resistance in a thermistor change with temperature?
The resistance decreases as the temperature increases.
How does the resistance in an LDR as the light falling on it get brighter?
The resistance decreases as light increases.
Why is the current the same throughout a series circuit?
Because the current has only one route, with no other alternative routes of varying resistance.
What happens to p.d in series circuits?
It is shared.
What does the p.d of all the components add up to?
The p.d of the power supply.
What happens to resistance in series? How is total resistance calculated?
The resistance increases by adding resistors. The total resistance is the resistance of R1 + R2 etc.
What is the relationship between resistance and p.d of a component in series?
The greater the resistance of a component, the bigger its share of the p.d.
Why is the potential difference the same in parallel?
Each component is connected across the supply potential difference.
Why is current shared in parallel?
There are different paths for it to flow through. The amount of current depends on the component’s resistance.
What is the relationship between the resistance and current of a component in parallel?
The greater the resistance, the lower the current through the component.
How is total current in parallel calculated?
By adding up the current from each component.
How does resistance change in parallel?
The total resistance decreases when adding more resistors. The total resistance of two or more resistors is always less than the resistance of the component with the least resistance.
