1.    a.       microwaves vibrate water or fats, vibrations heat food

       b.       waves can vibrate cells in your body, which can kill or damage them

2.    electrons, nucleus, neutrons

3.    a        i       727.0

                 ii       727 x 8p = £58.16

       b        2kW x 3 hours = 6 units

       c        i       P= current x Voltage = 59.8W

                 ii       Charge = current x time = 0.26 x 30 x 60mins x 60 seconds = 28080 C

4.    a        i       one arrow rising from heater, another arrow further away falling

                 ii       convection

                 iii       warm air expands à  it is less dense than surrounding air à rises.  Then it cools and falls

       b       reduces radiation losses by reflecting radiation back into the room

       c       double glaze window, insulate cavity walls, carpets, roof tiles …

5.    a       nucleus absorbs neutrons à splits (called fission) à 3 more neutrons emitted à cause more fission event à chain reaction

       b        Long half life à radioactive for 1000s of years

       c        240 / 80 = 3 half lives.  After 3 half lives 1/8 remains à 7/8ths have decayed

6.    a        i       5x10 = 50

                 ii       p=F/A = 0.3

       b        B – same force (weight) but smallest area

7.    a        i       electrons move from cloth to ruler

                 ii       positive

       b        i       oil drops all have same charge, repel

                 ii       opposite charge to oil drops à attract

       c        i       lightening

                 ii       conduction rods built into the sides of tall buildings, conducts charge safely to Earth

8     a       X=weight

              Y=friction / drag /  resistance of oil …

       b        i       increasing

                        X  is greater than Y

                 ii       steady speed, Y increases with increasing velocity until Y=X (terminal velocity)

       c        Area = 2 x 2.4 = 4.8cm

9     a        i       step up voltage to v high V

                 ii       step down V to safe levels

       b        high voltage means low current à less energy lost as heat  à more efficient transfer of electricity

       c        a.c. generates a changing magnetic field, changing M field required for induction of 2^nd coil

10    a       transverse, at right angles to, longitudinal, along or parallel to, electron magnetic or light, diffraction

       b        as the wave hits a density change it reflects some of the wave.  The time delay between A and B on the scope à position of flaw,if speed of sound in material is known

       c        i       radio waves diffract around the house

                 ii       T.V waves are shorter in wavelength.  Diffraction occurs best when the wavelength = obstacle size.

11    a       roughly circular, due to gravitational attraction between planet and sun

       b       weather monitoring, communications

       c        their orbits often take them a long way from the sun.

1.    a       gravitational, more

       b       gravitational potential, kinetic, thermal

2     a        3 core, each separately insulated, surrounded by another insulation

       b       bLue=neutral (on Left) brown = live (on Right)

3     a        coal, gas, nuclear, oil

       b       energy, water, steam, turbine, generator

4.    a        C

       b        zig-zags down tube via total internal reflection, as each interior angle of light within glass is greater than the critical angle