SP10 - Electricity and Circuits ✓ Flashcards Preview

Edexcel GCSE Physics COPY > SP10 - Electricity and Circuits ✓ > Flashcards

Flashcards in SP10 - Electricity and Circuits ✓ Deck (42)
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1

SP10a - Describe the structure of an atom including features of the sub-atomic particles.

  • Proton and neutron in the nucelus, each with a relative mass of 1.
  • Protons have a charge of +1.
  • Electrons orbit in energy levels each with a charge of -1 and a relative mass of 1/1835 (negligible)

2

SP10a - Descirbe what a potential difference is.

The force that pushes the electrons to flow around the circuit.

3

SP10a - What is conventional current?

What we refer to as the direciton of current form positive to negative. Opposite to the flow of electrons.

4

SP10a - What are the two types of circuits?

  • Series: everything connected in one route
  • Parallel: many options for different routes.

5

SP10a - Why may parallel circuits be more beneficial?

  • If the circuit becomes incomplete along one path, the rest of the circuit can still continue to function. (e.g - Switches can be connected to different parts meaning lights in parallel to each other can be switched in and off individually)
  • If a bulb goes off, the rest of the circuit in parallel to this can still continue to function

6

SP10b - What is the unit for current and how can it be measured?

Amps (Amperes). Measured using an ammeter which is attached in series to the circuit

7

SP10b - What is the unit for potential difference and how can it be measured?

Volts. Measured using a voltmeter which is attached in parallel to the component you are measuring the potential difference of.

8

SP10b - How does total current differ in parallel and series circuits?

  • S: The total current is the same at all points throughout the circuit
  • P: The total current gets split between the branches of the circuit, inversely proportionate to the resistance of the components in those branches.

9

SP10b - How does potential difference differ in parallel and series circuits?

  • S: The p.d is different across different components, directly proportionate to the resistance of that component
  • P: The p.d is tha same at all points across the circuit

10

SP10c - What is current?

  • The flow of electrons
  • The rate of flow of charge

11

SP10c - What is the unit for charge?

C - Coulombs

12

SP10c - What is the equation linking charge and current?

Q = I x t

(Charge = Current x time)

13

SP10c - What equation links energy and charge and how can this be changed to link energy to current?

E = Q x V (Energy = Charge x p.d)

since Q = I x t, this means that

E = I x t x V (Energy = Current x time x p.d)

14

SP10d - What is Ohm's law?

V = I x R

(p.d (V) = Current (A) x Resistance (Ω))

15

SP10d - What is resistance?

The force pushing back against p.d opposing and reducing the current.

16

SP10d - How do you calculate the resistance in series and parallel circuits?

  • Series: Add up the resistance of all the components
  • Parallel:  1/RT = 1/R1 + 1/R+ ...........

17

SP10d - What is key to remember about the size of the total resistance in series and parallel and series circuits?

  • S: It is greater than any of the individual resistances
  • P: It is smaller than all of the individual resistances

18

SP10e - What does a IV graph for fixed resistor look like and why?

  • It is a straight diagonal line showing direct proportion.
  • This is because resistors are ohmic conductors.
  • The voltage is directly proportionate to the current.

19

SP10e - What is an ohmic conductor?

A component in a circuit that follows Ohm's rule of V=IxR

20

SP10e - What does the gradient of an IV graph represent?

The inverse of the resistance (1/R)

21

SP10e - What does a IV graph for diode look like and why?

  • A line that is nearly on the x-axis till it shoots up.
  • This is because a diode has an infinitely high resistance till a point where it has an infinitely low resistance

22

SP10e - What does a IV graph for filament lamp look like and why?

  • An S shaped 'curve'.
  • This is because the resistance of a lamp increases due to the temperature increase as it conducts electricity at a higher voltage

23

SP10e - Describe what a graph for resistance of a thermistor would look like and why.

  • The x-axis would be temperature (°C) and the y-axis would be resistance (Ω)
  • As the temperature increases, the resistance decreases. This forms a negative curve in an L shape
  • This can be used to reduce the current in lower temperatures.

24

SP10e - Describe what a graph for resistance of an LDR (Light-dependant resistor) would look like and why.

  • The x-axis would be light intensity (lux) and the y-axis would be resistance (Ω)
  • As the light intensity increases, the resistance decreases. This forms a negative curve in an L shape
  • This is used for lit up signs outside. In darker conditions (lower light intensity) bulbs don't need to be as bright.
  • Thus, the resistance is higher to reduce the current and brightness
  • Resistance is high against the dark side #Starwars

25

SP10e CP - Describe your set-up for an experiment to compare the relationship of V=IxR in a resistor, and a filament lamp in parallel/series.

  • Set up a series circuit with a power pack, an ammeter, a fixed resistor and a voltmeter in parallel to this.
  • Provide different voltages from the power pack.
  • For each voltage provided, note down the current - Replace the fixed resistor with a lamp and repeat
  • Set up the circuit from here so that there is a voltmeter attached in parallel to this.
  • Attach another lamp to the circuit with another voltmeter in parallel to this
  • Measure out the voltages and currents when different voltages are supplied
  • Move one of the bulbs with its voltmeter to a new branch forming a parallel circuit
  • Add an ammeter to each branch of the circuit
  • Now measure the voltage and current depending on the voltage provided

26

SP10f - What is the heating effect?

  • The heating effect is when a circuit warms up due to the resistance in its wires.
  • Work is done against the resistance and so energy is transferred.
  • This is in the form of heating and dissipates into the surroundings

27

SP10f - Where is the heating effect useful?

  • In appliances such as electric heaters and kettles where the aim is to use thermal energy, the heating effect is incredibly useful.
  • In these circuits, resistance tends to be high.

28

SP10f - Describe what resistance is in terms of a metal's structure.

  • Current is the flow of electrons.
  • A metal is made of electrons flowing around positive metal ions
  • When the electrons are moving in the circuit, they can collide into these posistive metal ions.
  • These collisions are resistance and they transfer energy

29

SP10f - How can resistance be reduced in a circuit?

  • Choosing a metal with a lower resistance
  • Using a thicker wire (more space for electrons to flow)
  • Using a shorter wire (less distance in which they can collide)

30

SP10f - What formula links energy, time and voltage?

E = I x t x V

Energy = Current x time x Voltage