electrical charge and currenr Flashcards

1
Q

what is current

A

flow of electrical charge (flow of electrons)

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2
Q

what is a resistor

A

slows down flow of electrons / charge

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3
Q

what is a diode

A

allows current to flow in one direction only protect the components of the battery is the wrong way round

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4
Q

what is an LED

A

Special type of diode that glows when electricity passes through it

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5
Q

what is a thermistor

A

thermistors are used as temp sensors, their resistance decreases as the temperature increases. at low temp the resistance of a thermistor is high and little currently can flow through them

at high temp the resistance of a resistor is low and more current can flow through them

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6
Q

what’s a LDR

A

detects light levels. their resistance decreases as light intensity increases. in the dark and at low light levels resistance of an LDR is high and little current can flow through it. in bright light , resistance of an LDR is low, and more current can flow through

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7
Q

what do u use to measure current

A

ammeter

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8
Q

equation for total charge

A

Q=IT

I= current (amps )
T= time (seconds )
Q= charge (coulombs)
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9
Q

what is potential difference

A

a cell supplies energy to a charge to move it through the circuit and produce a potential a potential energy difference at one end of the circuit compared to the other , this creates a PD

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10
Q

what conclusion can u make abt current in a series circuit

A

current is the same

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11
Q

what conclusion can u make abt potential difference in a series circuit

A

potential difference is shared

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12
Q

what conclusion can u make abt current in a parallel circuit

A

current is shared

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13
Q

what conclusion can u make abt potential difference in a parallel circuit

A

potential difference is the same

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14
Q

what does current through a component depend on

A
  • resistance of component

- potential difference across component

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15
Q

equation for potential difference

A

V=IR

V= potednail diff (voltage)
I= current (A)
R= resistance
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16
Q

how does increasing the length or wire change the current

A

increasing length of wire decreases the current as it takes longer for the electrons to flow but the potential difference increases so the resistance is higher

as length of wire increases the resistance increases. resistance is directly proportional to length of wire

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17
Q

what does resistance slow down

A

flow of electrons

18
Q

what happens in a series circuit when u increase the amount of resistors

A

the total resistance increases so the electrons flow slower

19
Q

what happens in a parallel circuit when u increase amount of resistors

A

the total resistance decreases so the flow of electrons is faster because voltage is same but current increases

20
Q

why does total resistance decrease in parallel circuit

A

both resistors have the same potential difference but adding a extra loop, the current has more than one direction to go in. this increases the total current. an increase in current means a decrease in total resistance

21
Q

what isn’t an ohmic conductor

A

bulb and diode

22
Q

what is an ohmic conductor

A

resistor

23
Q

what is OHM’s law

A

the potential difference (voltage) across an ideal conductor is directly proportional to the current through it when the temperature is constant

components that follow this law are called ohmic conductor

24
Q

what happens to atoms in filament bunk when temp increases

A

atoms in metal filament vibrate more as the temperature increases. they resists the passage of the electrons through the filament more. the resistance increases as its temp increases

25
Q

what is direct current

A

flow of charge is in one direction

26
Q

what is alternating current

A

flow of electrons alternates

27
Q

3 things abt AC

A

current is consistently changing
voltage alternate
UK mains supply (230V 50hZ)

28
Q

3 things abt DC

A

Current is flowing in same direction
voltage is the same
batteries supply this

29
Q

in the plug which wire is where

A

N- neutral wire (blue) bottom left

E- earth wire (green &yellow) middle

L- live wire (brown ) right

30
Q

how can we remember order of wires

A

Never Eat Lemons

Neutral Earth Live

31
Q

what does the neutral wire do

A

completes circuit and carries current away (0V)

32
Q

what does earth wire do

A

protect the wiring and safety ( carries currently if there is a fault ) 0V

33
Q

what does live wire do

A

provide the alternating potential difference (230V)

34
Q

what does the fuse do

A

allows currently of certain valves to pass through. thin piece of metal wire melt to prevent large current to pass through component

35
Q

what is the national grid

A

the electrical power is transferred from power station through the step- up transformer which increases the potential difference from 25,000 V to 132,000 V which reduces the energy dissipated to the surroundings. at the step- down transformer it decreases the current and increases the voltage which makes it safer for the home with mains electricity at 230 V

36
Q

what does a battery with a bigger potential difference supply

A

a battery with a bigger potential difference will supply more energy to circuit for every coulomb of charge which flows around it

37
Q

equation for energy transferred

A

E=QV

E= emery transferred ( J)
Q= charge flow (coulomb )
V= potential difference (V)
38
Q

when is energy transferred electrically

A

energy is transferred electrically from the mains ac supply to the thermal energy store of the heating element inside the hairdryer

39
Q

how is energy transferred by heating

A

energy is transferred by heating from the thermal energy store of the heating element to the thermal energy store of the room

40
Q

talk about power eating

A

the lower the power rating the less electricity an appliance uses at a given time

but the higher the power doesn’t mean it transfers more energy usefully