mark scheme stuff Flashcards
what happens to ammeter when extra resistors are connected in parallel circuit
MP1. resistance (of circuit) decreased;
MP2. (because) extra path in circuit;
MP3. resistance (of circuit) halved;
MP4. idea that voltage across parallel branches is
the same (as previous voltage);
MP5. current (in ammeter) increased;
MP6. current (in ammeter) doubled;
why is there an alternating current in a ring that is detected underground from a metal detector
idea of changing magnetic field
idea of gold ring cutting field lines;
ignore ring interacting
with field
idea of induced voltage for gold ring;
how does A.C in receiving coil cause sound to be emitted from loudspeaker
MP1. alternating current in loudspeaker;
MP2. magnetic fields interact (in loudspeaker)
MP3. causing a force (on loudspeaker cone);
MP4. a.c. causes changing force direction;
MP5. loudspeaker (cone) vibrates;
Suggest why isotopes with a much shorter half-life are not suitable for
this investigation.
idea that count rate needs to be constant
during the investigation
allow
either
idea that would not
need to replace the
source often/ORA;
or
idea that shorter half-life has higher activity
and therefore is more
hazardous;
Granite is a rock.
It contains a radioactive isotope of uranium that decays very slowly.
(i) Explain how scientists can use this radioactivity to find the age of a piece of granite
any FOUR from:
MP1. there is a known proportion / composition /
activity when rocks formed;
MP2. measure/determine the proportion of
uranium or the activity now;
MP3. compare activity now to original activity/eq;
MP4. (hence) determine the time / number of
half-lives elapsed;
MP5. (hence) calculate age from reference to
half-life;
Suggest why the age of a piece of granite could not be found using a uranium
isotope with a half-life of 15 hours.
MP1.
idea that it/half-life is too short
OR
idea that decay occurs too quickly/rapidly;
PLUS
MP2. (hence)
U / isotope would (all) have decayed (long ago)
OR
U activity would be too small (to distinguish from
background / to measure);
radiation precaution and disposing
Radiation from Cobalt 60 can cause cancer and damaged cells, as it is highly penetrating. It can also contaminate land or water if it is not disposed properly. This is why special facilities are required to dispose
Cobalt 60. It is also transported in Lead containers to minimize damage.
loudspeaker
the loudspeaker produces a sound wave because the current in the coil is alternating and produces a magnetic field. because it is alternating the direction of the magnetic field is continuously changing. the magnetic field of the coil interacts with the magnetic field of the magnet producing a force on the coil. the direction of the force changes, causing the coil to vibrate. because of the coil vibrating the air particles next to the cone also vibrate producing a sound wave.
why does air rise upwards
air is heated so the air will expand this will cause it to rise and its density will decrease so then it will continue to rise upwards
nuclear fusion in a star
two (small) nuclei; 3
join together (to produce a large nucleus);
releasing energy;
cat x has no fur and light skin cat y has black fur, describe how energy transfers occurs for both
MP1. cat X loses more energy by conduction / convection than
cat Y;
MP2. cat Y loses more energy by radiation than cat X;
MP3. fur traps air;
MP4. larger surface area increases conduction (losses);
MP5. air is a (good) insulator/ poor conductor;
MP6. fur is a (good) insulator / poor conductor;
MP7. trapped air cannot move around;
MP8. trapped air reduces convection;
. MP9. black surfaces are better emitters / emit radiation faster;
component x is a resistor, where should a lamp be put so its voltage increases when component x voltage decreases
lamp should be connected in parallel with
component X / LDR;
3
resistance of component X increases when it gets
dark;
voltage across component X increases / becomes
greater than 10V when it gets
evolution of rigel and sirus
both stars begin as a nebula and both where a protostar and both are now main sequence stars. rigel has a high mass and become a red super giant, sirus will eventually be a white dwarf
hazards in kitchen
MP4. Idea overloaded cables or
sockets;
MP5. Idea of trip hazard from
trailing cables;
Do not use extension cables;
MP6. Idea of misusing
equipment e.g. sticking metal
objects into a socket or
exposed heating element;
Appropriate training/safety
regime, e.g. use of ‘blanks’
to cover sockets that
children can reach; cause
shock;
Use proper (insulated)
MP1. Idea of water in contact
with something electrical e.g.
plugs/sockets/switches;
MP2. Idea that an electrical
device with a heating element
reaches a high temperature;
MP3. Idea that damaged
equipment poses a hazard;
idea that insulation can
melt and cause a fire;
Live parts should not be
exposed;
can cause
shock;
leaky microwave radiation
can cause cancer;
total internal reflection def (2)
MP1. Idea that the reflection is (from a within
surface) inside the material;
MP2. Idea that all of the light is
reflected;
MP3. Idea that reflection occurs inside
the optically more dense medium;
MP4. light incident at angle greater than
critical angle
what if refractive index increases for the medium light will go into?
what happens inside the prism
ONE mark from:-
MP1. (blue light will) refract more (at the first
surface);
MP2. it will be nearer the normal;
MP3. ‘r’ will be smaller;
what happens on emergence:-
ONE mark from:-
MP4. it will bend even more;
MP5. so larger deviation than previously;
plastic lid on a plastic cup waffle r the results
Energy transferred by radiation decreases, equilibrium temperature will be higher, time taken to cool to room temperature will be longer
