13 Circuits - 4th Form Flashcards
Why are the bulbs dimmer in the second circuit?
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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?
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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?
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bulb
What component symbol is shown below?
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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
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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?
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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?
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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
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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