GENERA; Flashcards
Hairdryer takes current of 5.5A Why should you use a 7A fuse (1)
Nearest above
Hairdryer has a plastic case so there is no need for an earth wire connection in the plug. Explain why the hairdryer is still safe to use (2)
- Plastic insulator / doesn’t conduct
- No risk of shock / electrocution
Describe how the student should use each instrument to make her measurements as accurate as possible. (4)
Measuring cylinder; Electronic balance
MC - flat surface, eyes to water level
EB - Set to zero, avoid disturbing balance
For a density experiment, state one factor that she should keep the same throughout her experiment and why (2)
- Temperature
- Can affect density/volume
What is refraction (1)
- Change in direction of waves at a boundary
- draw around block
- mark positions of incident and emergent rays
- (remove block and) draw refracted ray
- measure i; measure r
- range of values;
- (graph of) sin i against sin r
- graph is straight line
- gradient gives refractive index
Why would a pattern show a uniform magnetic field (1)
- Parallel field
Explain how to produce a uniform magnetic field (3)
- two (permanent / bar) magnets
- pole pieces north facing South
- magnets the correct distance apart
Describe the method the teacher should use to correct for background radiation. (3)
- Remove source
- measure background
- find mean
- subtract (background value) from experimental values (with source);
Technetium-99 is a gamma emitter with a half-life of 6 hours. Radioactive tracer in medicine.
Technetium-99 is injected into a patient’s bloodstream and carried around the body by the blood.
The radiation it emits is detected outside the body. Explain why technetium-99 is suitable for use as a tracer in this way.
(3)
- (gamma) can be detected outside the body
- long enough half life to get around the body (for use as tracer)
- half life falls to low levels soon after use;
Describe how a sound wave moves through the air. (3)
- oscillation of (air) molecules
- longitudinal
- directions of vibration and propagation are parallel
- compression / rarefaction /pressure wave;
Which force is responsible for artificial satellites following their paths around the Earth? (1)
- Gravity
Moons are natural satillites of…(1)
- Planets
State one similarity in the movement of planets and comets.
State one difference between the movement of planets and comets. (2)
- Both orbit the sun
- Different shape orbit
Explain how the speed of a comet changes as it moves. (2)
- Speeds up closer to sun
- gravitation attraction from the Sun is stronger when the comet is close
Suggest two safety precautions you should take when putting a plug into a mains socket (2)
- beware of frayed cable
- beware of damaged plug
- beware of water
Describe the difference between a.c. and d.c. (2)
d. c. – electrons/current motion only in one direction
a. c. – electron/current motion reverses (regularly)
Describe how the earth wire can act together with a fuse as a safety device. (2)
- large current in earth wire / charge flows to earth
- large current in fuse ; fuse melts
- stopping electrocution
Explain why a mains plug can be safe to use even though it has no earth connection. (2)
- double insulation of plug, cable or appliance
- insulation stops current / does not conduct
- electric shocks are currents idea of a second insulation layer in case the first fails
Describe how the students should find the average mass of a winged seed (2)
- Measure using balance
- Repeated readings
Describe how radioactivity can be used to estimate the age of archaeological discoveries such as wooden boats and animal bones. (4)
- (living things contain) carbon (14)
- C14 is a beta emitter
- (radio)activity decreases (over time)
- (estimate) half-lives (since material was alive)
- ratio of C14 to C12 is fixed in living material
Compare the processes of transferring energy by conduction and transferring energy by convection (3)
- CONDUCTION: from particle to particle
- by collision
- CONVECTION: particles able to move
- transfer the energy by kinetic energy
Useful light energy emitted in J/s : 5
Describe what happens to the energy wasted by the filament lamp. (2)
- transformed into thermal energy
- dissipated to surroundings
State two benefits of connecting lamps in parallel. (2)
- independent control
- failure of one allows others to continue working
State two conditions required for total internal reflection to happen. (2)
- Must be more (optically) dense to less (optically) dense change;
- Angle of incidence > critical angle;
The image in a plane mirror is a virtual image.
How can you tell this from your diagram? (1)
- Rays do not actually meet at the image
Suggest 3 advantages of sending signals using optical fibres. (3)
- Less prone to noise
- less prone to heating
- send more information (per second)
- more data (per second)
Describe the method the student should use to investigates how the resistance of a wire depends on its length (5)
- connect (crocodile) clip to wire
- Read ammeter and read voltmeter
- For known length
- measure length with a ruler
- Repeat readings in different places along the wire
- Take readings for different lengths
- Check meters for zero errors
- Disconnect/switch off between readings
- To avoid heating the wire;
How to make a measuring cylinder give the most precise measurement? (1)
- Smallest scale divisions
The most precise measuring cylinder may not give an accurate reading. Suggest why. (1)
- incorrect scale / calibration
- misreading scale / parallax /not at eye level
- meniscus makes it difficult to read
- might not be level / flat; reading may be between divisions;
Explain how nuclear fission can lead to a chain reaction. (3)
- Nucleus splits
- Releasing neutrons
- Which are absorbed by different (uranium) nuclei;
Nuclear fission releases energy. Explain the form that this energy takes. (2)
Kinetic (energy of particles)
- Of (fission) products / (daughter) nuclei / neutrons
In a nuclear power station, what is the purpose of a moderator (1)
- Slow down neutrons
Suggest 2 properties of radio waves that makes them suitable for use in communication. (2)
- Travel quickly / at the speed of light
- Can code information
Can travel long distances / through buildings / walls / objects
Not harmful/dangerous; can diffract / reflect;
Harmful effect of microwaves (1)
Heating
Use and harmful effect of UV rays (2)
Use : flourescent lamps
Harmful effect : sunburn
Describe how a loudspeaker uses an electrical supply to produce sound waves. (5)
- alternating current in coil
- produces magnetic field
- (constantly) changing (field)
- which interacts with field of permanent magnet
- force on coil
- vibration in coil
- making longitudinal wave;
The gravitational field strength is smaller on the Moon than on the Earth. Suggest why. (1)
- Moon has less mass
The feather reaches the ground after the hammer, even though the force of air resistance is smaller on the feather than on the hammer. Explain why the feather reaches the ground after the hammer.
(4)
- Feather is lighter
- reaches terminal velocity
- before hammer
- because smaller (drag) force needed
- (so) average velocity of feather is lower / falls slower;
Use ideas about particles to explain how a gas causes a pressure on the inside of a container. (3)
particles in constant motion / particles have kinetic energy
- in random directions
colliding with walls
causing a force on the walls
Pressure = force /area;
How would increasing the temperature of the compressed air affect the pressure in the can?
Explain your answer. (3)
- Increases pressure
- (higher temp) increases (average) speed / kinetic energy of particles
- So collide with walls more often / at higher speed;
A power of 1 watt is the same as…
1 joule per second
Two uses and two dangers of UV (4)
Uses - Flourescent lamps, killing bacteria
Dangers - Cell and eye damage, suburn
Add to the diagram to show field lines
Describe how to investigate the shape and direction of the magnetic field between two magnets (3)
- a method to show shape
- Use of iron filings
- sprinkle iron filings evenly on card
- tap card to distribute iron filings
Describe the motor effect (2)
- (Fleming’s) Left Hand (Motor) rule
- there is a force on rod
- translational movement of rod
- out of the paper
A student wants to find density
He has the mass.
What else must he do to find the density (3)
- Measure/find volume
- Using a displacement method
- repeat readings and find average
- Formula to use (density = mass ÷ volume)
- density unit mentioned (e.g. kg/m3);
A racing cyclist rides around a track. A student wants to find the average speed of the cyclist. What should he do (5)
- measure distance and time
- measure time using stopwatch, distance using tape measure
- Count laps (of known length);
- repeat experiment/calculate average;
- Speed = distance / time
- time from a predetermined consistent point;
What are the products of the fission of uranium nuclei (3)
- Neutrons
- Daughter nuclei
- Gamma radiation
The distance between earth and mars varies. Explain why (2)
- Different speeds
- Different orbits
Why is speed limited to 0.04 m/s for the Mars rover (2)
- low speed reduces stopping distance
- low (kinetic) energy reduces damage if in collision
Explain why it is difficult to measure the thickness of a single piece of paper with a ruler (2)
- ruler has a mm scale
- idea of inappropriate precision
- paper is (very) thin;
Explain what is meant by the term ‘half life’ (2)
- Time taken
- For radioactivity to halve
Describe what happens in a reactor when a control rod is removed (2)
- rate of reaction increases
- fewer neutrons absorbed by control rod
Describe the difference between transverse waves and longitudinal waves. You may draw diagrams to help your answer. (3)
- oscillations (vibrations) are at right angles to the direction of travel and energy transfer (transverse)
- oscillations are along the same direction as the direction of travel and energy transfer.
The extension cable is fitted with a 13 A fuse. Describe how the fuse protects the cable. (3)
- if current exceeds 13A
- fuse (wire) melts
- breaking circuit
- prevents cable over heating;
The extension cable is fitted with a 13 A fuse. Explain why a 5 A fuse is not suitable for this extension cable. (2)
- limits the use of the extension cable
- can’t reach max working value
- (because otherwise) 5 A fuse will blow
Describe an experiment to investigate the shape of the magnetic field pattern of a bar magnet. (3)
Place magnet under paper / plastic
Sprinkle iron filings over
- Tap paper gently (to reveal pattern);
Describe how the student should measure the starting height of the car. (2)
- Use a ruler
- Held vertically
- check for zero errors
Write a plan for the student’s investigation. Your plan should include details of how the student can make accurate measurements.
You may add to the diagram to help your answer. (5)
- Add (known value) masses one at a time
- Measure length of the spring
- Find extension
- Draw graph with suitable named axes
- measure from same part each time
- Make sure spring stationary before reading
- repeat readings by taking off masses
- Check value of masses on a balance
- Check ruler vertical to spring
Explain what is meant by the term elastic behaviour. (2)
- returns to original length / shape
- when (stretching) force is removed;
State two properties of electromagnetic waves that makes microwaves suitable for communications with a satellite in space. (2)
- travel very fast
- can be coded
What effect does the emission of a beta particle have on a nucleus? (2)
- neutron number decreases by 1
- proton number increases by 1
Explain why radioactive sources can be dangerous. (2)
- (they emit) ionising radiation
- Cannot be seen
- Can damage/harm cells
- Can cause tumours / cancer;
Describe how the risks of working with radioactive sources can be reduced. (3)
Reduce exposure time
- keep at distance
- Use shielding e.g gloves
- Wear film badge
Suggest how the student could measure the volume of an inflated balloon. (2)
- measure water displaced (with measuring cylinder)
- calculate volume (with equation);
Suggest how the student measured the area of the floor in contact with his foot. (3)
- Record outline of foot
- Attempt at evaluation of area
- estimate the squares
- on squared paper
Describe how a detector can be used with sheets of lead, aluminium and paper to show that a sample of sodium-24 emits beta particles. (2)
- beta penetrates paper
beta absorbed by lead +/or aluminium
Use ideas about forces to explain how a falling object can reach a terminal velocity. (5)
- There is a downward force due to gravity on the object
- So it accelerates (downwards)
- there is a force of drag upwards
- drag increases as speed increases
- eventually drag = weight
- (hence) resultant force is zero
- (hence) object travels at constant speed;
Describe how an earth wire acts as a safety feature. (4)
- earth connected to (metal) casing
- Live wire touches case
- Provides low resistance path (to earth)
- (So) large current in earth wire
- (hence) fuse breaks/melts/blows
- (so) circuit switches off or current stops or supply cuts off;
The photograph shows a small electric motor. Explain why the coil starts to spin when the switch is closed. (4)
- Current in coil
- (Creates) magnetic field (around the wires of the coil)
- Interaction of (this) field with that of (permanent) magnets
- There is a force on the wire(of coil)
- left hand rule
- force up on one side and down on other side;
Suggest how to make the coil spin in the opposite direction. (1)
- Swap magnets over
- Reverse current direction
The diagram shows how air moves near the coast on a warm day. Explain why air moves as shown on the diagram. (5)
- Energy (transferred) from the sun
- Air over the land is heated
- Warmer air over land expands
- Air becomes less dense and therefore rises
- Cooler air over sea becomes denser
- Cooler air over sea sinks
- Air (from over the sea) moves inland to replace rising air;
Explain how Brownian motion provides evidence that air is made of small particles. (3)
- smoke particles are large particles
- larger particles move with random motion
- collisions with smaller (invisible) particles
State a difference between the orbit of a moon and the orbit of a planet. (2)
- a moon orbits a planet
- a planet orbits a star /the Sun
Explain why shielding is needed in a nuclear reactor (2)
- Reactor material / waste is radioactive
- (radiation) ionises cells/ tissues / organs / body or causes cancer
- radiation is very penetrating;
Largest mass out of beta gamma alpha (1)
alpha
Highest speed out of beta gamma alpha (1)
gamma
Suggest why alpha radiation is more ionising than beta or gamma radiation. (1)
- Charge is larger
- Mass is larger
Suggest why fewer alpha particles reach the detector if there is a fire. (2)
- α particles are absorbed
- α particles are affected by smoke;
- air molecules heated by the coal fire
- air expands
- air becomes less dense
- less dense air rises
- cooler air from outside the furnacedisplaces warm air
- above the chimney air cools/becomes more dense
- cooled air falls
- convection) is repeated
Describe how the student could measure the volume of a non-uniform shape. (4)
- displacement method
- measure volume (of liquid displaced) measuring cylinder
- full immersion of object
- avoid parallax when reading scale
- use of known liquid density to find volume from mass
Water from a reservoir can be used to generate electricity on a large scale. Describe the energy transfers involved in this process. (3)
- water has initial GPE
- KE of (moving) water
- Work done on turbine / generator
- Work done against magnetic force
- Electrical energy (produced);
ii
- friction/resistance /drag (acts)
- (there is an) unbalanced force
- (hence) ball decelerates
- f(R )= ma
- (kinetic) energy dissipates
Explain why a data logger records a varying voltage. (2)
- current is induced
- (because) field in coil is changing
- voltage changes direction when magnet does
- magnet slows down causing decrease in amplitude;
One way orbits between earth are different (1)
- Different orbital radius
