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Physics > P2 Revision > Flashcards

P2 Revision Flashcards

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1
Q

What are components

A

A device in an electric circuit, such as a battery, switch or lamp

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2
Q

What is a fixed resistor

A

restricts or limits the flow of electrical current, the resistance does not change

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3
Q

Variable resistor

A

A resistor where the value of the resistance can be changed

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4
Q

Thermistor

A

An electrical device whose resistance decreases as its temperature increases- can be used in thermostats

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5
Q

Light dependent resistor (LDR)

A

A type of resistor which is affected by changes in light levels. Low light levels = high resistance, higher light intensity = resistance decreases

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6
Q

Name 2 types of current

A
  • direct
  • alternating
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7
Q

What happens in a direct current

A

The flow of electrons is in one direction only

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8
Q

What happens in alternating current

A

The direction of electron flow continually reverses

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9
Q

What is charge

A

A property of a body which experiences a force in an electric field (measured in coulombs)

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10
Q

What is the equation for charge

A

Charge = current x time
Q = I x t
Charge = coulombs
Current = amps
Time = seconds

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11
Q

What is current measured by

A

An ammeter

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12
Q

What does the current depend on

A
  • the resistance of the component
  • potential difference across the component
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13
Q

How do you measure potential difference across a component

A

A voltmeter must be placed in parallel with that component
- potential difference is known as voltage

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14
Q

What is the equation for potential difference

A

Potential difference = energy/charge
V = E/Q

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15
Q

What is the resistance over a longer piece of wire compared to a shorter piece of wire

A

The resistance is higher over a longer piece of wire. Resistance is directly proportional to length of wire

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16
Q

What is a diode

A

An electrical device that allows current to flow in one direction only

17
Q

What is Ohm’s law

A

The rule that states that the current is directly proportional to the voltage across the resistor - provided that temperature remains constant

18
Q

What is the series circuit?

A

A circuit, where one component follows directly from another.

19
Q

Important key facts for series circuits

A

Current is the same through each component
The total potential difference of the power supply is shared between the components
The total resistance of the circuit is the sum of individual resistors

20
Q

What does current do in a parallel circuit

A

The current will split
An ammeter can show/measure how the current splits

21
Q

What happens to potential difference (voltage) in a parallel circuit

A

The potential differences is supplied equal across each of the parallel components

22
Q

What happens when resistors are added to a parallel circuit?

A

The overall resistance is reduced as the current (electrons) may follow multiple paths

23
Q

Why do wires heat up

A

Electrons flowing through wires, collide with ions Which causes the ions to vibrate more. increasing temperature.

24
Q

Power and measurements

A

Power (watts) = current (amps) x potential difference (volts)

Power(watts) = current^2(amps)
x resistance (ohms)

25
Q

What colour are the earth, neutral and live wire

A

Earth = green and yellow
Neutral = blue
Live = brown

26
Q

What is the national grid

A

The network that connects all the power stations in the country to make sure that everywhere has access to electricity

27
Q

What are transformers?

A

An electrical device that increases or decreases the potential difference (voltage) of an alternating current

28
Q

Why do objects sometimes become electrically charged when rubbed against each other

A

Electrons which are negatively charge may be ‘rubbed off’ one material and onto the other. Leaves a positive and negative charge on the objects

Charges may attract or repel

29
Q

How to draw an electric field

A

Arrow drawn from positive to negative charge
Closer together arrows are, stronger the force

Physics (6 decks)

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