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Current is different at different points in a series circuit.
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True or False?
Current is different at different points in a series circuit.
False.
Current is the same everywhere in a series circuit.
True or False?
In a parallel circuit, the current from the power source is larger than the current in each branch.
True.
In a parallel circuit, the current from the power source is larger than the current in each branch.
True or False?
The amount of current flowing in a series circuit depends on the voltage and resistance in the circuit.
True.
The amount of current flowing in any circuit depends on the voltage and resistance in the circuit.
True or False?
Current is conserved at a junction in a parallel circuit.
True.
Current is conserved at a junction in a parallel circuit because charge is always conserved.
True or False?
Current always splits equally at a junction in a parallel circuit.
False.
Current will only split equally at a junction if the resistance in each branch is equal.
True or False?
When several cells are connected in series, their combined voltage is the product of their individual voltages.
False.
When several cells are connected in series, their combined voltage is the sum of their individual voltages.
What is the rule for determining the total voltage in a series circuit?
The total voltage across the components in a series circuit is equal to the sum of the individual voltages across each component.
What is the rule for determining the total voltage in a parallel circuit?
The total voltage across an arrangement of parallel resistances is the same as the voltage across one branch in the arrangement of the parallel resistances.
True or False?
One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.
True.
One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.
True or False?
One advantage of a series circuit is that if one component fails the others will still work.
False.
An advantage of parallel circuits is that if components in one branch fail, the components in other branches will still work.
If one component fails in a series circuit, then the circuit is broken and the current cannot flow.
What is the rule for calculating the combined resistance of two or more resistors in series?
When two or more resistors are connected in series, the combined resistance is the sum of the individual resistances.
True or False?
The combined resistance of two resistors in parallel is less than that of either resistor by itself.
True.
The combined resistance of two resistors in parallel is less than that of either resistor by itself.
State the equation for calculating the combined resistance of two resistors connected in series.
The equation for calculating the combined resistance of two resistors connected in series is
Where:
= the total combined resistance, measured in ohms (Ω)
= the resistance of the first resistor, measured in ohms (Ω)
= the resistance of the second resistor, measured in ohms (Ω)
If the voltage of the power source remains constant, but more components are added to a circuit, what effect does this have on the current?
Adding components to a circuit increases the total resistance of the circuit, so the current would decrease (for a constant voltage).
If the voltage of the power source is increased, but everything else in the circuit remains constant, what effect does this have on the current?
If the voltage of the power source is increased, but everything else in the circuit remains constant, the current will increase.
What does the gradient of an I-V graph represent?
The gradient of an I-V graph represents the resistance of a component.
What does a linear I-V graph show?
A linear I-V (current-voltage) graph shows
the relationship between current and voltage is directly proportional
the resistance of the component is constant
Which component has the following I-V graph?
This is the I-V graph for a fixed resistor or a wire (at a constant temperature).
Which component has the following I-V graph?
This is the I-V graph for a filament lamp.
Which component has the following I-V graph?
This is the I-V graph for a diode.
True or False?
As the current through a filament lamp increases, the resistance decreases.
False.
As the current through a filament lamp increases, the resistance increases.
Why does the resistance of a filament lamp change when the voltage is changed?
The resistance of a filament lamp increases as the voltage is increased because
as the current increases, the lamp heats up
as the temperature increases, metal ions in the filament wire vibrate more
the amount of collisions between the ions and free electrons increases
What are the main features of an I-V graph for a diode?
The I-V graph for a diode shows they have
a high resistance when the current flows in one direction
a low resistance when the current flows in the opposite direction
What is the difference between a fixed resistor and a variable resistor?
The resistance of a fixed resistor is constant, whereas the resistance of a variable resistor can be changed.
The circuit symbol for a variable resistor has an arrow through it, whereas the symbol for a fixed resistor does not.
List five pieces of apparatus needed to investigate the relationship between current and voltage of a component.
The five pieces of apparatus needed to investigate the relationship between current and voltage of a component are
an ammeter
a voltmeter
a variable resistor
a power source
wires
What is a thermistor?
A thermistor is a temperature-dependent resistor.
This means its resistance changes depending on its temperature.
How does the resistance of a thermistor change when its temperature is increased?
When the temperature of a thermistor is increased, its resistance decreases.
What is an LDR?
LDR stands for light-dependent resistor.
This means its resistance changes depending on the intensity of light on it.
How does the resistance of an LDR change when the intensity of light on it is increased?
When light intensity on an LDR is increased, its resistance decreases.
(Remember: Light Decreases Resistance - LDR)
Sketch a graph to show the relationship between resistance and temperature for a thermistor.
For a thermistor, the relationship between resistance and temperature is
Sketch a graph to show the relationship between resistance and light intensity for an LDR.
For an LDR, the relationship between resistance and light intensity is
What is an LED?
An LED is a light-emitting diode.
It is a type of diode, meaning it only allows current to flow in one direction.
True or False?
Lamps and LEDs can be used to indicate the presence of a current in a circuit.
True.
Lamps and LEDs can be used to indicate the presence of a current in a circuit.