PPQ PAPER 1 Flashcards
Different charging systems use different electrical currents. Charging system A has a current of 13 A. whilst Charging system B has a current of 26 A. The potential difference of both charging systems is 230 V. How does the time taken to recharge a battery using charging system A compare with the time taken using charging system B?
time taken using system A is double the time of system B
It is unlikely that all of the electricity that the UK needs can be generated by solar power systems. Explain why.
a really large area of land would need to be covered with solar cells due to the low useful power output of the solar cells
Student A investigated how current in a resistor at constant temperature varied with the potential difference across the resistor. Student A recorded both positive and negative values of current. Describe a method that Student A could use for this investigation.
- measure the current in R using the ammeter and measure the p.d. across R using the voltmeter
- vary the resistance of the variable resistor
- record a range of values of current and p.d.
- ensure current is low to avoid temperature increase
- switch circuit off between readings
- reverse connection of R to power supply
- repeat measurements of I and V in negative direction
- plot a graph of current against p.d.
It is dangerous for a person to fly a kite near an overhead power cable. The person could receive a fatal electric shock if the kite was very close to, but not touching the power cable. Explain why.
electric field strength is very high causing the air to become ionised (the kite / string) conducts charge to the person / earth
A duster’s handle is made of an insulator and attached to a large quantity of nylon fibres. When the duster had been used, the nylon fibres spread out from each other and dust is attracted to the duster. Explain why the claim the duster attracts dust ‘like a magnet’ is untrue.
The attraction to the dust is due to attraction to the duster due to electrostatic force, whereas a magnet attracts and repels due to a magnetic field.
Suggest why the alpha particle experiment was carried out in a vacuum
Air contains particles made up of atoms. These could be hit by the alpha particles.
Give 2 reasons why Xenon-133, which emits beta radiation and has a half-life of 5 days, is used for investigating problems with the lungs.
the half life is very short so it is unlikely to do long-tern harm. Xenon is a gas so breathed directly to the lungs, which is the area under investigation.
Suggest the safety precautions staff need to take when using radioactive therapy treatments with patients.
- wear a personal monitoring badge to monitor personal exposure
- move away from patient when administering treatment to minimise chance of radioactive contamination
- use survey meters to warn of radioactivity
- use shielding to prevent radiation getting to the hospital staff
A freezer is at -10 degrees. Over time, ice cubes in an ice-cube tray in the freezer shrink. What is the name of the process that the water in the ice cubes is undergoing?
sublimation
CO2 undergoes sublimation at 1 atmosphere pressure and -78.5 degrees. If the pressure changes to 5.1 atmospheres then liquid CO2 can form. Explain why CO2 can change from a solid to a liquid when the pressure is at 5.1 atmospheres.
when the pressure is high enough, the CO2 molecules are unable to get enough energy to move directly to the gas from and instead have enough energy to move to the liquid phase
Arwen investigated how the resistance of a wire changes with length. Suggest why Arwen did not take any measurements under 20cm.
the wire would heat up which is a safety issue and would cause changes in the resistance of the wire not related to its length
Explain the role of control rods in a nuclear reactor
absorb neutrons without themselves fissioning
A negatively charged rod is held near to an earthed conductor. Explain why a spark jumps between the negatively charged rod and the earthed conductor.
- there is a large potential difference between the conductor and the rod
- this causes electrons to move, creating a current, from rod to conductor
