Define potential divider .

A potential divider is a circuit that produces an output voltage that is a fraction of its input voltage, using two or more resistors in series.

State three purposes of a potential divider circuit.

To provide a variable potential difference To enable a specific potential difference to be chosen To split the potential difference of a power source between two or more components

In a potential divider, how does increasing the resistance of one resistor affect the potential difference across it and across the other resistor?

The resistor with increased resistance gets a greater share of the potential difference; the other resistor gets a smaller share.

In a potential divider circuit, the resistor with the .......... resistance has the greatest potential difference across it.

In a potential divider circuit, the resistor with the largest resistance has the greatest potential difference across it.

True or False? In the potential divider equation, the resistor in the numerator is always R 1 .

False. The resistor in the numerator is always the resistor that V out is measured across, whichever resistor that is.

Define potentiometer .

A potentiometer is a variable resistor connected as a potential divider that gives a continuously variable output voltage, and can be used to compare potential differences in a circuit.

How is a potentiometer recognised on a circuit diagram?

As a resistor fitted with a sliding contact .

What effect does the sliding contact have on a potentiometer?

It separates the potentiometer into an upper part and a lower part , each with a different resistance .

If the slider of a potentiometer is moved so the resistance of the lower part increases, what happens to the potential difference across the lower part?

It also increases , since p.d. is proportional to resistance.

A potentiometer gives a .......... variable output voltage.

A potentiometer gives a continuously variable output voltage.

True or False? The output voltage of a potentiometer can only take two fixed values: maximum or minimum.

False. The output voltage varies continuously between a minimum and maximum value as the slider moves.

Define galvanometer .

A galvanometer is a sensitive ammeter used to detect small electric currents; it is used in a potentiometer to measure e.m.f. between two points in a circuit.

What is a galvanometer made from?

A coil of wire wrapped around an iron core that rotates inside a magnetic field .

What is meant by 'null deflection' on a galvanometer?

When the needle points directly upward, showing that no current is flowing through the galvanometer.

How must the cell be connected relative to the potentiometer wire for a galvanometer to reach a null point?

So that its potential opposes the potential on the wire, i.e. positive terminal facing positive terminal.

A galvanometer has zero p.d. when the potential on one side .......... the potential on the other side.

A galvanometer has zero p.d. when the potential on one side equals the potential on the other side.

True or False? A galvanometer shows zero deflection whenever any current, however small, flows through it.

False. A galvanometer shows zero deflection (null) only when there is no current at all flowing through it.

Define LDR (Light Dependent Resistor) .

An LDR is a resistor whose resistance decreases as light intensity increases (and vice versa); used in sensory potential divider circuits, e.g. street and security lights.

A thermistor is a resistor whose resistance decreases as temperature increases (and vice versa); used in circuits such as fire alarms, ovens and digital thermometers.

In a potential divider, if the resistance of a sensory resistor decreases, what happens to the potential difference across it?

It also decreases , since p.d. is proportional to resistance (from V = IR ).

If the p.d. across a sensory resistor in a potential divider decreases, what happens to the p.d. across the other resistor?

It increases , since the total p.d. of both components must equal V in .

LDR circuits are often used for street and .......... lights.

LDR circuits are often used for street and security lights.

True or False? In a potential divider containing a thermistor, if the temperature increases, the p.d. across the thermistor also increases.

False. As temperature increases, the thermistor's resistance decreases , so the p.d. across it also decreases .

A LevelPhysicsCambridge (CIE)Flashcards10. D.C. CircuitsPotential Dividers

Potential Dividers (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontPotential Dividers
Define potential divider.
FrontPotential Dividers
State three purposes of a potential divider circuit.
BackPotential Dividers
To provide a variable potential difference
To enable a specific potential difference to be chosen
To split the potential difference of a power source between two or more components

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Cards in this collection (24)

Define potential divider.
A potential divider is a circuit that produces an output voltage that is a fraction of its input voltage, using two or more resistors in series.
State three purposes of a potential divider circuit.
- To provide a variable potential difference
- To enable a specific potential difference to be chosen
- To split the potential difference of a power source between two or more components
State the potential divider equation for the output voltage V_out across resistor R₂ in a series circuit of R₁ and R₂.
$V_{o u t} = \frac{R_{2}}{R_{1} + R_{2}} V_{i n}$
In a potential divider, how does increasing the resistance of one resistor affect the potential difference across it and across the other resistor?
The resistor with increased resistance gets a greater share of the potential difference; the other resistor gets a smaller share.
In a potential divider circuit, the resistor with the .......... resistance has the greatest potential difference across it.
In a potential divider circuit, the resistor with the largest resistance has the greatest potential difference across it.
True or False?
In the potential divider equation, the resistor in the numerator is always R₁.
False.
The resistor in the numerator is always the resistor that V_out is measured across, whichever resistor that is.
Define potentiometer.
A potentiometer is a variable resistor connected as a potential divider that gives a continuously variable output voltage, and can be used to compare potential differences in a circuit.
How is a potentiometer recognised on a circuit diagram?
As a resistor fitted with a sliding contact.
What effect does the sliding contact have on a potentiometer?
It separates the potentiometer into an upper part and a lower part, each with a different resistance.
If the slider of a potentiometer is moved so the resistance of the lower part increases, what happens to the potential difference across the lower part?
It also increases, since p.d. is proportional to resistance.
A potentiometer gives a .......... variable output voltage.
A potentiometer gives a continuously variable output voltage.
True or False?
The output voltage of a potentiometer can only take two fixed values: maximum or minimum.
False.
The output voltage varies continuously between a minimum and maximum value as the slider moves.
Define galvanometer.
A galvanometer is a sensitive ammeter used to detect small electric currents; it is used in a potentiometer to measure e.m.f. between two points in a circuit.
What is a galvanometer made from?
A coil of wire wrapped around an iron core that rotates inside a magnetic field.
What is meant by 'null deflection' on a galvanometer?
When the needle points directly upward, showing that no current is flowing through the galvanometer.
How must the cell be connected relative to the potentiometer wire for a galvanometer to reach a null point?
So that its potential opposes the potential on the wire, i.e. positive terminal facing positive terminal.
A galvanometer has zero p.d. when the potential on one side .......... the potential on the other side.
A galvanometer has zero p.d. when the potential on one side equals the potential on the other side.
True or False?
A galvanometer shows zero deflection whenever any current, however small, flows through it.
False.
A galvanometer shows zero deflection (null) only when there is no current at all flowing through it.
Define LDR (Light Dependent Resistor).
An LDR is a resistor whose resistance decreases as light intensity increases (and vice versa); used in sensory potential divider circuits, e.g. street and security lights.
Define thermistor.
A thermistor is a resistor whose resistance decreases as temperature increases (and vice versa); used in circuits such as fire alarms, ovens and digital thermometers.
In a potential divider, if the resistance of a sensory resistor decreases, what happens to the potential difference across it?
It also decreases, since p.d. is proportional to resistance (from V = IR).
If the p.d. across a sensory resistor in a potential divider decreases, what happens to the p.d. across the other resistor?
It increases, since the total p.d. of both components must equal V_in.
LDR circuits are often used for street and .......... lights.
LDR circuits are often used for street and security lights.
True or False?
In a potential divider containing a thermistor, if the temperature increases, the p.d. across the thermistor also increases.
False.
As temperature increases, the thermistor's resistance decreases, so the p.d. across it also decreases.

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