PHYSICS MISTAKES

describe the stages in the evolution of a star similar in mass to the sun (4)

• nebula to protostar

• protostar to main sequence

• main sequence to red giant

• red giant to dwarf

• white dwarf to black dwarf

energy release in stars

• NUCLEAR FUSION

• fusion of the joining of the nuclei

• involves light nuclei

energy release in reactors

• NUCLEAR FISSION

• splitting of the nuclei

• involves heavy nucleus

HOOKE’S LAW

• idea that extension is (directly) proportional to force or load

• up to limit of proportionality

why does a ray of light not change direction when it enters the atmosphere

• angle of incidence is 0

• therefore the angle of refraction is also 0

describe how a loudspeaker in the radio converts a.c. signal to a sound wave (4)

describe an experiment to determine the emission of technetium-99 is gamma radiation (5)

• use a GM tube

• measure background count rate

• measure count (rate) with source;

• subtraction to) find corrected count (rate);

• repeat readings to obtain mean;

• idea that paper / aluminium does not affect count / reading;

• idea that lead reduces count rate significantly;

explain how the doppler effect cuases a change in the observed frequency of the waves

• speed of waves constant;

• if source moving away, wavefronts spread out / wavelength increases;

• speed = frequency × wavelength;

• (higher wavelength and constant speed of waves) gives lower frequency;

which quantity is defined as the rate of flow of charge?

current

which quantity is defined as the energy transferred per unit charge passed?

voltage

explain how the design og the cup keeps the drink hot refer to methods of energy transfer (6)

• cup stops energy transferred to the surroundings

• RELATES TO CONDUCTION

  • contains no particles

  • reduces conduction

  • plastic lid is a poor conductor

• RELATES TO CONVECTION

  • air is trapped by the lid

  • reduces convection

• RELATES TO RADIATION

  • shiny surface is a poor absorber of infrared radiation

  • outer shiny surface is a poor emitter of infrared radiation

  • energy transfer by radiation is stopped

explain the change in frequency when the car is moving towards of a person (4)

• frequency increases

• pitch increases

• wavefronts are closer together

• wavelength decreases

• due to the Doppler effect

why would the results of a radioactive source decaying not lie on the curve of best fit?

decays RANDOMLY

types of waves

TRANSVERSE: oscillations that travel perpendicular to the direction of the wave

LONGITUDINAL: oscillations that travel parallel to the direction of the wave

how will the reading of an ammeter change in parallel if there are 2 identicals LEDs?

• resistant decreases

• because of extra path in the circuit

• resistance is halved

• current increases