P2.2 Controlling and Using Electric Currents Flashcards
What is a series circuit?
A series circuit is a circuit where the current only flows through one loop
What is a parallel circuit?
A circuit in which there are multiple ways which current can flow.
What happens to the current at a junction in a parallel circuit?
It splits in two.
How do you change the current in a circuit?
To change the size of the current you can change the potential difference. The higher the voltage the the bigger the current.
How do you measure voltage?
To measure the potential difference, the amount of energy energy transferred by a component, we use a voltmeter. The voltmeter is placed parallel to the component.
What is 1 volt equal to?
1 volt is equal to 1 joule per coulomb. This is because the potential energy measures the energy transferred to a component for each unit of charge that passes through that component. As energy is measured in joules and and charge is measured in coulombs.
What is the equation for resistance?
Volts=current x resistance.
What is resistance?
Resistance determines the size of the current flowing the circuit along with the voltage. Resistance measures how hard it is for a current to flow and is measured in higher the resistance the smaller the current.
How can we change the resistance?
The resistance can be changed with a variable resistor.
How do filament lamps change resistance?
When being used, filament lamps heat up. The higher Th voltage, the hotter the lamp gets, and as they get hotter the resistance increases.
How do diodes change resistance?
Diodes conduct electricity in only one direction. If the potential difference is applied in the other direction no current will flow.
How do LDRs effect resistance?
The resistance LDR is large in the dark, but not large in the light.
How do thermistors resistance?
When cold p, thermistors have very high resistances and when they are hot, they have a lesser resistance.
What is an ammeter?
An ammeter is the component which is placed in a circuit to measure current.
Why do resistors get warm?
When current flows through a resistor, energy is transferred to it and the resistor become warm. This is useful in appliances like kettles and electric fires, which are essentially large resistors.
What happens in a motor?
In motors energy transfer is from electrical to kinetic. However hear energy is also produced, this is waste energy. Some electrical appliances produce so much waste energy that they get too hot and burn people.
How is energy transferred?
A current is a flow of electrons. As the electrons move in the metal they collide with the ions in the lattice and transfer energy to them.
What is the equation for power?
Power= current x potential difference.
What is the equation for energy transferred?
Energy transferred= current x potential difference x time.
