13 Circuits - 4th Form Flashcards
Why are the bulbs dimmer in the second circuit?
Voltage is shared between bulbs in series
Less voltage across each bulb therefore bulb is dimmer.
Define voltage
Energy per unit charge either supplied by a cell, or transferred to a component.
What component symbol is shown below?
Light dependent resistor
What is voltage measured in?
Volts or V
What is the voltage across a cell or power supply a measure of?
The energy transferred from chemical store electrically to the wires per coulomb
What component symbol is shown below?
bulb
What component symbol is shown below?
ammeter
Define current
- The rate of flow of charge
OR
- the number of coulombs passing a point in a circuit per unit time
(It is not the speed of the electrons!)
What happens to the total resistance and current in a circuit as more bulbs are added in parallel
Adding bulbs in parallel decreases the total resistance
V=IR
I = V / R
as resistance decreases, current increases for the same voltage
How will the current change if the resistance of a circuit is decreased for the same voltage?
current will increase
To investigate how the currect varies with voltage in a filament bulb, fixed resistor and diode you should use the cirucit below.
Why does the circuit need a variable resistor?
To vary the voltage across the component
Independent variable is voltage
Dependent variable is current
What is resistance?
- The tendency of a material to resist the flow of an electrical current.
- A measure of how much voltage is needed per amp of current.
How does the resistance vary with light intensity on a LDR?
As light intensity increases, resistance decreases
What is a volt?
1 V = 1 J/C
1 volt = 1 joule per coulomb
How does voltage related to current and resistance?
V=IR