5.3 - Circuits & The Potential Divider Flashcards

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1
Q

What is the combined resistance of resistors in series?

A

RT = R1 + R2 + R3…

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2
Q

What is the combined resistance of resistors in parallel?

A

1/RT = 1/R1 + 1/R2 + 1/R3…

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3
Q

What is the current of the components in a series circuit?

A

They are all the same current.

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4
Q

What is the current of the components in a parallel circuit?

A

Depends on the branch.
The amount of current in each depends on RT in the branch.
IT into junction = IT out of junction

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5
Q

What is Kirchhoff’s 1st law?

A

The total current that enters a junction is equal to the total current that leaves the junction.

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6
Q

What is the voltage flowing through components in a series circuit?

A

The e.m.f of the power supply is shared amongst all the components in different amounts depending on their resistance.

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7
Q

What is the voltage flowing through components in a parallel circuit?

A

The voltage of all the components in each branch is equal to the e.m.f of the power supply.

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8
Q

Is charge conserved in a circuit?

A

It is never used up or lost in a circuit so yes.

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9
Q

What is a junction?

A

A point where at least 3 circuit paths meet.

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10
Q

What is a branch.

A

A path connecting 2 junctions.

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11
Q

What is Kirchhoff’s first law in numbers?

A

I = I1 + I2 + I3

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12
Q

What is Kirchhoff’s 2nd law?

A

The total e.m.f in a closed circuit equals the sum of the potential differences across each component.

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13
Q

What are the equations for power?

A

P = E/t
P = IV
P = I²R
P = V²/R

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14
Q

What can the formula for energy be written as?

A

E = VIt
(voltage, current, time)

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15
Q

What are potential dividers?

A

A circuit with several resistors in series connected across a voltage source, used to produce a required fraction of the source potential difference, which remains constant.

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16
Q

What are the 2 main purposes of potential dividers?

A
  • 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 2 or more components
17
Q
A
18
Q

What is the potential divider equation?

A

Vout = (R2 / R1 + R2)Vin

19
Q

What is an LDR?

A

A sensory resistor (like a thermistor) which stands for light dependent resistor.

20
Q

What is the symbol for a LDR?

A

A rectangle with 2 arrows pointing at it.

21
Q

With LDR, what is the relationship between light intensity and resistance?

A

The higher the light intensity, the lower the resistance.
The lower the light intensity, the higher the resistance.

22
Q

What is the relationship between Vout from a resistor in a potential divider circuit?

A

The potential difference is proportional to its resistance.
LDR/thermistor’s resistance decreases, p.d decreases (vice verse)