Electricity And Energy Flashcards
(35 cards)
What is the Current?
The current is the rate of flow of charge.
What is the current in a circuit measured using?
An Ammeter.
What is Direct Current?
Direct Current moves in one direction only (from negative to positive) and the size of the current is constant in size and direction.
Where is DC usually supplied from?
A battery.
What is Alternating Current?
Alternating current constantly changes size and direction.
Where is AC usually supplied from?
The Mains.
What is the Mains Supply in the UK?
230 Volts.
What is the Voltage?
Voltage is the energy supplied per unit charge.
What is Voltage measured by?
A Voltmeter.
How must a voltmeter be connected in order to measure the voltage across a component?
In parallel with the component.
In what type of circuit is the current the same at all points?
A Series Circuit.
I1=I2=I3
In which type of circuit is the Voltage shared between components?
A Series Circuit.
Vs=V1+V2
In which circuit does the current split between branches?
In a Parallel circuit.
I1=I2+I3
In which circuit is the voltage equal across each branch?
In a Parallel Circuit.
Vs=V1=V2
Note: The voltage across each branch is equal but the voltage across components on one branch will not always be equal.
What is the resistance like in a series circuit?
In a series circuit the total resistance is equal to the sum of the resistance of each component.
Rt= R1+R2
What is the resistance like in a parallel circuit?
1/Rt=1/R1=1/R2
This means that when resistors are added in parallel the total resistance in the circuit decreases.
What is the power rating of an appliance?
The power rating of an appliance is the energy it transfers per second.
What is a fuse?
A fuse is a safety device which will stop current flowing if the current becomes too high. This avoids appliances overheating and starting fires.
Is an appliance has a power rating of over 720 watts which type of fuse will it contain?
A 13A fuse
If an appliance has a power rating below 720W what type of fuse will it contain?
A 3A fuse.
Why is a resistor connected in series with an LED?
To limit the current in the LED.
What is a Transistor?
A transistor is a voltage-controlled switch.
The voltage across which resistor determines whether the transistor turns on?
The voltage across the bottom resistor.
How does light affect the resistance of an LDR?
If the light level decreases, the resistance of the LDR will increase, therefore the voltage will increase.
If the light level increases, the resistance of the LDR will decrease, therefore the voltage will decrease.
