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Physics > EP 1 > Flashcards

EP 1 Flashcards

1
Q

What is lubrication

A

Liquids like oil that reduce frictional forces

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2
Q

Does the resistance of ohmic conductors change with current

A

No

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3
Q

What are sensing circuits

A

Used to turn on or increase power to components depending on conditions

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4
Q

How many volts is the U.K.’s main supply

A

230v

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5
Q

What is the frequency of the AC mains supply

A

50 Hz

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6
Q

What does the power rating tell u

A

Maximum amount of energy transferred per second in appliance. For example lower power rating, less electricity so cheaper to run

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7
Q

Y doesn’t a higher power rating mean it transfers more energy usefully

A

Could be less efficient

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8
Q

What does the national grid use

A

High PD (400000v) and a low current

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9
Q

What is static caused by

A

Friction and only electrons move not positive charges

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10
Q

What is a positive static charge caused by

A

Electrons moving away as electrons loses some negative charge so left with equal positive charge

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11
Q

What does too much static cause

A

Sparks

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12
Q

What are sparks caused by

A

Potential difference gets large enough electrons jump across gap between charged object and earth

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13
Q

When a charged object is placed in the electric field of another object what does it feel

A

A force

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14
Q

What happens when air is ionised

A

It’s conductive so current can flow through it causing a spark

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15
Q

When a substance changes state what happens to the number of particles

A

Stays the same

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16
Q

What is specific latent heat

A

Amount of energy needed to change 1 kg of it from one state to another without changing its temperature

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17
Q

What is the specific latent heat for changing between a solid and liquid

A

Specific latent heat of fusion

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18
Q

What is the specific latent heat for changing between a liquid and gas

A

Specific latent heat of vaporisation

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19
Q

Is pressure and volume inversely or directly proportional to each other

A

Inversely

20
Q

If you increase the temperature of a gas what energy store does it transfer into

A

Kinetic energy stores

21
Q

What can doing work on a gas increase

A

Its temperature

22
Q

What is half life ACTIVITY measured in

A

Becquerels Bq

23
Q

What is 1 Bq equal to

A

1 decay per second

24
Q

What does a short half life mean

A

Activity falls quickly because nuclei very unstable and rapidly decay. Can be dangerous because high amount of radiation but quickly become safe

25
Q

What does a long half life mean

A

Activity Falls slowly because most nuclei don’t decay for a long time can be dangerous because nearby areas are exposed to radiation for years

26
Q

What is the radiation dose measured in

A

Sieverts sv

1sv = 1000 millisieverts msv

27
Q

Does irradiating something make it radioactive

A

No

28
Q

What affects radiation dose

A

X-rays and where you live

29
Q

Examples of background radiation

A

Unstable isotopes, cosmic rays, human activity

30
Q

What is contamination

A

Radioactive particles getting onto objects which can cause you harm as it can get in your body

31
Q

How can you prevent contamination

A

Use gloves and tongs when handling sources to avoid particles to get in your skin or under nails and wear protective suits to stop breathing in particles

32
Q

What radiation is most dangerous to the outside of the body

A

Beta and gamma as they penetrate the body and to get to organs whereas alpha can’t penetrate ski and is blocked by a small air gap

33
Q

What radiation is most dangerous inside the body

A

Alpha because damage in very localised area so more contamination.

34
Q

Why is beta less damaging inside the body

A

Radiation is absorbed over wider area

35
Q

Why is gamma less damaging inside the body

A

Radiation passes straight out and lowest ionising power

36
Q

What isotopes r taken into the body

A

Gamma emitters as they have a short half life

37
Q

What r gamma sources used in

A

Medical traces

38
Q

How do mutant cells divide

A

Uncontrollably this is cancer

39
Q

What is nuclear fission

A

Type of nuclear reaction used to release energy from large unstable atoms by splitting them into smaller items

40
Q

What is nuclear fusion

A

Joining small nuclei and releases a lot of energy

41
Q

What is sublimation

A

Solid to a gas

42
Q

I-v circuits practical

A
  1. Set up test circuit see page 43
  2. Vary variable resistor to alter current and potential difference flowing through component
  3. Take several pair readings from ammeter and voltmeter to compare pd and current across component. Repeat twice to get average pd.
  4. Swap wires connected to cell so direction of current is reversed
  5. Plot graph of current against voltage
43
Q

Investigating resistance practical

A
  1. Attach crocodile clip to wire at 0cm on ruler
  2. Attach second crocodile clip to wire and write down length of wire between clips
  3. Close switch record current and pd across wire
  4. Open switch move second crocodile clip along wire close switch record new length current pd
  5. Repeat this then calculate resistance and plot graph of resistance against wire length and draw line of best fit.
  6. Should be directly proportional if it doesn’t go through origin first clip isn’t attached at 0 systematic error
44
Q

What does an ammeter measure

A

Current in amps must be placed in series

45
Q

What does a voltmeter measure

A

Potential difference in volts must be placed in parallel

Physics (6 decks)

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