Electric Circuits Flashcards
What is static electricity?
When an object becomes electrically charged.
What happens with friction?
Electrons are transferred from one object to another.
What happens when you rub a polythene rod?
The electrons are transferred from to the rod from the cloth. The rod becomes negatively charged.
What happens when you rub a Perspex rod with a cloth?
Electrons are transferred from the rod to the cloth. The rod becomes positively charged. It’s positive charge is equal to the negative charge of the dry cloth.
What is an electric field?
Two charged objects exert a non-contact force on each other because of this charge. The charged object creates an electric field around itself. The second charge object experiences a charge because of this field.
What is an electric current?
A flow of charge. Millions of an electron pass through a cell every second.
What determines the size of an electric current?
The rate of flow of electric charge. The bigger the amount of electrons that passes through a component each second, the bigger is the current passing through it.
What is the current like in a single, closed group circuit?
It is the same at any point in the circuit. This is because the number of electrons that passes through any part of the circuit is the same way any other part.
What is an electric current of one ampere equal to?
Rate of flow of charge of one coulomb.
What is a diode?
It allows the current through it in a certain direction and only when it is connected.
What is potential difference?
The energy transferred to the bulb or work done on it by each coulomb of charge that passes rough it.
What does a resistor do?
Limits the current.
Why is a wire called an ohmic conductor?
It’s resistance stays constant as the current changes.
What happens to the resistance of the filament lamp as the temperature increases?
The resistance increases. The resistance of any metal increases and the temperature increases. This is because the atoms in the metal filament begin to vibrate and this means that they resist the passage of electrons through the filament more.
What is a LED?
A diode that emits light when a current flows through it.
What is a thermistor?
A temperature dependent resistor. It’s resistance decreases if its increases.
What happens to the resistance in a light dependent resistor?
The resistance decreases as the light intensity increases.
What is the rule about the current in a series circuit?
In a series circuit, the same current passes through each component.
What is the rule about p.d. in a series circuit?
The total potential difference (of the power supply) is shared between components
The total p.d. of cells in series is the sum of the p.d. of each cell.
What is the rule about resistance in series?
The total resistance of two or more components in series is equal to the sum of the resistance of each component.
What happens when you add more resistors in series?
It increases the total resistance of the circuit.
This is because the total p.d. is shared between more resistors.
What is the rule about current in parallel circuits?
The total current through the whole circuit is the sum of the currents through separate branches.
What is the rule of p.d. In parallel circuits?
For components in parallel, the p.d. across each components is the same.
What happens when you add more resistors in parallel?
The total resistance of two (or more) components in parallel is less than the resistance of the resistor with the least resistance.
