13 Circuits - 4th Form Flashcards

1
Q

Why are the bulbs dimmer in the second circuit?

A

Voltage is shared between bulbs in series

Less voltage across each bulb therefore bulb is dimmer.

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2
Q

Define voltage

A

Energy per unit charge either supplied by a cell, or transferred to a component.

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3
Q

What component symbol is shown below?

A

Light dependent resistor

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4
Q

What is voltage measured in?

A

Volts or V

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5
Q

What is the voltage across a cell or power supply a measure of?

A

The energy transferred from chemical store electrically to the wires per coulomb

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6
Q

What component symbol is shown below?

A

bulb

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7
Q

What component symbol is shown below?

A

ammeter

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8
Q

Define current

A
  • 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!)

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9
Q

What happens to the total resistance and current in a circuit as more bulbs are added in parallel

A

Adding bulbs in parallel decreases the total resistance

V=IR

I = V / R

as resistance decreases, current increases for the same voltage

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10
Q

How will the current change if the resistance of a circuit is decreased for the same voltage?

A

current will increase

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11
Q

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?

A

To vary the voltage across the component

Independent variable is voltage

Dependent variable is current

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12
Q

What is resistance?

A
  • 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.
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13
Q

How does the resistance vary with light intensity on a LDR?

A

As light intensity increases, resistance decreases

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14
Q

What is a volt?

A

1 V = 1 J/C

1 volt = 1 joule per coulomb

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15
Q

How does voltage related to current and resistance?

A

V=IR

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16
Q

What is true about the current in a series circuit?

A

Current is the same everywhere in a series circuit

17
Q

What type of circuit is this? Series or parallel?

A

Series circuit

Only one path or branch in the circuit

18
Q

What are the prongs of a plug made of brass but the wires made of copper?

A

Brass is strong and will not bend

Copper is a good conductor of electricity and ductile (can be drawn into wires)

19
Q

What component symbol is shown below?

A

thermistor

20
Q

How does voltage across bulbs in a series and parallel circuit differ?

A

Current is conserved in all circuits

Series - current is the same everywhere in the circuit

Parallel - current splits between the branches- current into a junction equals current out of a junction

21
Q

What is the unit for current?

A

ampere / amps or A

22
Q

What component symbol is shown below?

A

buzzer

23
Q

What component symbol is shown below?

A

voltmeter

24
Q

What component symbol is shown below?

A

Fuse

25
Q

What component symbol is shown below?

A

Light emitting diode

26
Q

What component symbol is shown below?

A

motor

27
Q

Bulbs in series provide a larger resistance than bulbs in parallel

With this in mind, which circuit draws a larger current from the cell?

A

V = IR

I = V / R

as resistance decreases, the current increases for the same voltage

The second circuit draws a larger current from the cell, bulbs are in parallel and the total resistance is smaller than the first circuit (series circuit)

28
Q

Each cell provides 3 V. In which circuit (series or parallel are the bulbs brighter?

A

Bulbs in parallel are brighter = both have 3V across them (brighter)

Bulbs in series have 1.5 v across each (dimmer)

Series- voltage is shared - VCell = V1 + V2

Parallel - each bulb gets the full voltage of the cell - Vcell = V1 = V2

29
Q

How does current differ between series and parallel circuits?

A

Current is conserved in all circuits

Series - current is the same everywhere in the circuit

Parallel - current splits between the branches- current into a junction equals current out of a junction

30
Q

How does the resistance of an LDR vary with light intensity?

A

As light intensity increases, resistance decreases

31
Q

Describe what it means when 1 A is passing through a circuit

A

1 A = 1 Coulomb per second

32
Q

The IV graph below is for an ohmic conductor…

Give an example of an ohmic conductor.

A
  1. fixed resistor
  2. wire (if at constant temperature)
33
Q

Below is the IV graph for a….

A

filament bulb

34
Q

Explain why the second circuit draws a lower current from the cell?

A

circuit with two bulbs in series - has larger resistance

V=IR

I = V/R

as resistance increases, current decreases for same voltage

35
Q

What component symbol is shown below?

A

diode

36
Q

For a wire - as temperature increases, resistance also increases.

The graph below shows the opposite.

What component is this graph for?

A

Thermistor

37
Q

What component symbol is shown below?

A

variable resistor

38
Q

What component symbols are shown below?

A

battery/two cells

&

solar cell