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Physics > Section 7- Electricity And Cicruits > Flashcards

Section 7- Electricity And Cicruits Flashcards

1
Q

What’s the current ?
What’s current measured in?

A

-flow of electric charge around a Cicruit

-amps

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2
Q

What’s potential difference?
What else is potential difference called?
Unit?

A

-the driving force that pushes the charge around

-voltage

-Volts

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3
Q

What’s resistance?
Unit for resistance

A

-Anything that slows the flow down

  • ohm 🧲
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4
Q

Why will current flow through an electrical circuit?

A
  • if there’s a potential difference
  • if the circuit is closed (complete)
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5
Q

What does the current flowing through a component depend on?

A

Current flowing through a circuit Depends on the POTENTIAL DIFFERENCE and the RESISTANCE of the component

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6
Q

What happens to the current when there’s a higher potential difference ?

A

Higher current

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7
Q

Greater resistance = …. Current

A

Greater resistance = smaller current

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8
Q

How do currents move in metals?

A

-Metals are bonded in a lattice (positive ions surrounded by free electrons)

-these electrons are free to move through the metal

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9
Q

Do electrons move from positive—> negative or the other way around ?

A

Electrons move from positive to negative in a circuit

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10
Q

How is charge calculated?

A

Charge = current X time

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11
Q

How do you calculate potential difference using current and resistance ?

A

Potential difference = current X resistance

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12
Q

How do you calculate resistance?

A

Resistance = p.d /current

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13
Q

What does temperature increase along with?

A

Resistance

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14
Q

Why does resistance increase with temperature ?

A

Electrons collide with ions in the lattice that makes up the reuses or as they flow through it

Gives ions energy —-> causes them to vibrate more

The more the ions vibrate, the harder it is for electrons to get through a resistor as there are more collisions

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15
Q

2 types of circuits ..

A

Series circuits
Parallel circuits

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16
Q

What’s a series circuit?

A

All components are connected in a line

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17
Q

3 rules of a series circuit…

A

-The current is the same everywhere

-total potential difference of the supply is shared between components (pd of each component depends on its resistance)

-total resistance of circuit increases as you add resistors

18
Q

Why are parallel circuits more useful?

A

If you remove or disconnect one of the parts, it will hardly effect anything at all

19
Q

What happens to the potential difference across all the components in a parallel circuit?

A

All components get the full source of pd. all their pds will equal the full voltage supply

20
Q

What happens to the current in parallel circuits?

A

The current is shared between branches

21
Q

What does adding a resistor in a parallel curcuit do to resistance?

A

Decreases resistance

22
Q

Why does adding a resistor in a parallel curcuit decrease the resistance?

A

By adding another loop, the current has more than one direction to flow in.

This increases the total current

By using V=IR, an increase in current means a decrease in total resistance for a circuit

23
Q

What’s a series circuit?
Whats the current like in it?
Whats the potential difference like?
Whats the total resistance the sum off?

A

-Components all connected end to end.

-Current is the same everywhere

  • potential difference is shared across the circtuit ( PD of supply = sum of PD across each component)

-total resistant is the sum of the resistance across each component

-

24
Q

What’s a parallel circuit ? What happens to the current on each branch ?what the voltage like on each branch ? Why will two resistors in parallel have a smaller overall resistance than just one ?

A
  • blanched circuit

-current splits into multiple paths. Current of all branches adds to total current

-voltage is the same on each branch

  • because the charge will go along another branch , it has other options
25
Q

Equation for energy transfered…

A

E=QV

ENERGY TRANSFERRED = charge moved X potential difference

26
Q

Where should current be measured on a circuit? How’s it measured? V=

A

-Anywhere

-measured with an ammeter placed in series

V= IR

27
Q

How does resistance change current and temp and why?
W

A

Greater resistance makes it harder for the charge to flow through the component , therefore the currents smaller.

When electrons flow through revision, they collide with ions in the resistor. Current does work against resistance. This transfers energy to ions , making them vibrate more and making it difficult for current to flow through resistor. Same thing happens for temp

28
Q

Equation to find voltage …

A

V=IR

29
Q

Equation for charge ?

A

Q=IT

30
Q

2 equations for power…

A

P=IV
Power= current X voltage

P= I^2 X R
Power= current ^2 X resistance

31
Q

2 Equation’s for energy

A

E=PT
energy = power X time

E=QV
Energy = charge X voltage

32
Q

How does resistance change when youincrease length ?why?

A

Greater length = more resistance , therefore lower current

  • electrons need to make their way through more resistor ions, so it’s harder than if you use a short wire
33
Q

How does resistance change with light in an LDR?

A

Greater intensity of light, lower resistance . So resistance greatest when dark

34
Q

What is AC? Where does it come from ? What happens to the current

A

AC is alternating current, which comes from the mains
Current continuously varies from positive to negative

35
Q

What’s DC? What’s the movement of charge like? Where does it come from?

A

Dc is direct current which is the movement of charge in one direction only
Supplied by cells and batteries

36
Q

What Hz and V is the uk mains supply

A

50 Hz
230V

37
Q

What are the 3 wires in a plug?

A

Live wire
Neutral wire
Earth wire

38
Q

What’s live wire?

A

A brown wire that carries voltage from the mains to appliance

39
Q

What’s neutral wire?

A

A blue wire that completes the circuit

40
Q

What’s earth wire?whay it connected to?

A

-Green and yellow striped wire that acts as a safety wire to stop the appliance becoming live.

-The earth

41
Q

What does the fuse do?How

A

The fuse is connected to the live wire. If a large current passes through the live wire, fuse heats up and melts , breaking the circuit

Prevents a fire

Physics (11 decks)

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