| 16300580571 | How does your ear detect sound? | - Sound waves reach ear drum which vibrates
-Vibrations passed to ossicles, through semicurcular canal then to cochlea
- Cochlea turns vibrations into electrical signals which are sent to brain
- Brain interprets signals as different pitches and volumes depending on frequency + intensity (high freq, higher pitch) |  | 0 |
| 16301700772 | What is ultrasounds + how do you use it? | - Sound of freq above 20 000 Hz
- Used for ultrasounds, sonar, finding kidney stones, monitor blood flow
1) transmitter beams ultrasound waves into mother
2) waves reflect from different boundaries
3) machines calculates distances using time and velocity and uses distances to produce image | | 1 |
| 16300678632 | Describe sound waves | - Caused by vibrating objects
- Vibrations passed as compressions and rarefractions
- Longitudinal
- When changes media: speed changes (solids fastest), freq doesn't change, wavelength does change (longer when speeds up - sound waves refract)
- Reflected by hard surfaces, echoes
- Can't travel in a vaccuum | | 2 |
| 16300778537 | What happens when a wave meets a boundary? | - Absorbed, transfer energy to material's energy stores
- Transmitted, carries on, often different speed, refracted
- Reflected | | 3 |
| 16300863692 | Describe reflection (waves) | - Angle of incidence = angle of reflection
- smooth surfaces - clear reflection e.g mirror, rough surface (specular) - scattered reflections (diffuse) |  | 4 |
| 16300937497 | Describe refraction (waves) | - Wave changes speed in different densities, generally: denser = faster, but EM waves usually opposite.
- Freq stays same, wavelength changes.
- If slows down, bends toward normal + vice versa
-colours have different wave lengths, shorter wavelengths slow down, refract more |  | 5 |
| 16301134843 | Describe Oscilloscope experiment (measuring speed of sound) | 1) Set up oscilloscope + 2 microphones next to a speaker
2) Slowly move one away until 2 waves aligned on display
3) Measure distance between microphones to find wavelength
4) Use v=fλ to find speed, freq = whatever signal generator is set to | | 6 |
| 16301239720 | How do you use a ripple tank to measure frequency? | 1) float cork in tank, start stop watch
2) count number of bobs in 20 s
3) divide by tie to get frequency | | 7 |
| 16301277094 | How do you use a ripple tank to measure Wavelength? | 1) place cm squared paper behind tank
2) turn on strobe light + adjust frequency until wave appears to freeze
3) measure distance 5 waves cover.
4) divide distance by number of waves to get average wavelength | | 8 |
| 16301325393 | How do you use a ripple tank to measure wave speed? | 1) Place large piece of paper next to tank
2) Using ruler, draw line following top of 1 wave for 10 s
3) calculate speed by D x T | | 9 |
| 16301426924 | Label a transverse wave | |  | 10 |
| 16301471781 | What are transverse + longitudinal waves & give examples | Transverse: vibrations perpendicular to direction wave travel e.g. ripples, light
Longitudinal: vibrations are parallel to direction wave travels e.g.sound waves, P waves |  | 11 |
| 16301562720 | Describe Transformers | - Change size of the PD pf an AC
- Have primary + secondary coil joined w. iron core
- alternating PD applied to primary produces alternating magnetic field - core becomes magnetised + alternates too
- Changing magnetic field induces a PD in secondary coil.
- Step down (more in 1st), step up (more in 2nd), |  | 12 |
| 16301654393 | Describe an alternator | - Generate an alternating current
- A coil of wire rotating in magnetic field
- Coil connected to 2 commutators, allows current to pass out of coil.
- PD induced when wire cuts magnetic field
- Because 2 sides of coil attached to 2 different rings, produces alternating PD and an AC
To increase AC: increase field strength, increase no. coils, increase coil area, increase coil rotation speed | | 13 |
| 16302118755 | Describe a dynamo | - Produces a direct current
- Has a split ring commutator
- Coil cuts field, inducing PD and current
- Direction of PD and current do not reverse when coil rotates (DC) |  | 14 |
| 16304423203 | Explain how a microphone works | - Uses generator effect
- coil of wire attached to diaphragm, at other end coil sits on permanent magnet.
- sound waves hit diaphragm - it vibrates
- coil of wire moves in and out through magnetic field - induces a PD across the wire.
- PD passed through an amplifier, then into a loudspeaker |  | 15 |
| 16304560119 | Explain how a loud speaker works | - Cone with coil wrapped around, coil connected to an AC electrical supply, permanent magnet inside coil.
- current passes through coil - generates magnetic field
- field interacts with field from magnet, which attract/repel, causes cone to move, generating sound waves
- changing freq of AC supply, changes freq that cone vibrates, higher freq = higher pitch
- changing size of current changes amplitude of vibration - increases sound volume |  | 16 |
| 16304730566 | Describe how an electric motor works | - loop of wire carrying current in a magnetic field experiences a force on left + right side
- Fleming's left hand rule proves this ^^
- Loops will rotate, but once loop at 90 degrees will stop rotating as forces then change to push back to original position
- Solve by switching current direction when loop passes 90 degrees, use split ring commutator, connected to conducting brushes.
- current produces turning force on motor, current breaks (gap of commutator) but wire keeps turning due to momentum, current then switches direction. |  | 17 |
| 16304952977 | What is Fleming's left hand rule? | |  | 18 |
| 16305246996 | What does a solenoid do? | - Increases strength of magnetic field
- field like a bar magnet outside of coil, act like N and S pole
To increase effect:
increase current, increase coils, decrease cross-sectional area, decrease solenoid length, add iron core |  | 19 |
| 16305343981 | Describe the magnetic field around a wire | - Concentric circles with wire in centre
- Fleming's right-hand rule to find direction
- Compass can prove there's a current around wire |  | 20 |
| 16305536051 | How do you test whether an object is charged? | -Hold charged rod above object. Charged rod induces a charge, if rod is positive it attracts electrons, if negative, it repels electrons.
-Test if rod charged b holding near stream of water, stream will bend towards it. | | 21 |
| 16305629713 | Why is static caused? | - All matter contains charge ( + protons, - electrons)
- Neutral matter contains equal + and - (0 net charge) but charge can build up.
- 2 materials rubbed together, electrons transferred.
- If conductors, electrons flow back into/out of so stay neutral
- If insulators, electrons can't flow, positive static charge left on object which which lost electrons and vice versa. | | 22 |
| 16305849403 | Describe the electric charge on electric fields | - Charged objects have electric fields.
- POSITIVE TO NEGATIVE
- When fields around 2 charged objects interact, a force is produced (repulsion/attraction) |  | 23 |
| 16305973046 | What is current, PD and resistance? | current (A) = rate of flow of electrons around circuit, will only flow if there is a PD across component + circuit is complete
Potential difference (V) = driving force that pushes current round, the energy transferred per coulomb of charge.
Resistance (Ω) = how easily charge can flow
Usually: higher PD, higher current. Greater resistance, smaller current. | | 24 |
| 16306080693 | What is the I-V for resistors and wires | Current directly proportional to PD (if temp same) different resistors have different resistances so graphs can slope (still straight) |  | 25 |
| 16306186789 | What is the I-V graph for a filament lamp? | Increasing current increases temp which makes resistance increase so graph is curved. |  | 26 |
| 16306207155 | What is the I-V graph for a diode? | Current will only flow through diode in 1 direction, diode has v high resistance in opposite direction |  | 27 |
| 16306294220 | What is the circuit symbol for an LED? | |  | 28 |
| 16306304058 | What is the circuit symbol for a variable resistor | |  | 29 |
| 16306311059 | What is the circuit symbol for a diode? What is it? | - Device made from semiconductor material
- Lets current flow freely in 1 direction, not in other (V high resistance)
- Can be used to get direct current from an alternating supply |  | 30 |
| 16306319191 | What is the circuit symbol for an LDR? What is it? | - Resistor dependent on light
- Dark: resistance high
- Light: resistance low, current through LDR increases |  | 31 |
| 16306327400 | What is the circuit symbol for a thermistor? What is it? | - Temperature dependent resistor
- Hot: resistance drops
- Cool: resistance goes up
- In constant conditions, I-V graphs are curved, as current increases thermistor warms up, so resistance decreases
- Used as temperature detectors |  | 32 |
| 16306338985 | What are the circuit symbol for power supply terminals? | |  | 33 |
| 16306498257 | What is the difference between series and parallel circuits? | - Series circuits: components connected in a line, current only has one route, flows through all components, disconnecting one can have big effect
- Parallel circuits: Each component separately connected to +ve and -ve terminals of supply, disconnecting one hardly effects others |  | 34 |
| 16306583889 | What is the rule for PD is series circuits? | V = v1 + v2
Total PD is shared between components, PDs round ciruit add up to PD across power supply. | | 35 |
| 16306613632 | What is the rule for current in series circuits? | I1 = I2 = I3
Current is the same everywhere, same current flows through whole circuit. | | 36 |
| 16306645395 | What is the rule for resistance in series circuits? | R = R1 + R2 + R3
Resistance adds up, total resistance is sum of individual resistors.
The bigger the resistance of a component, the bigger the PD because more energy is transferred from charge when moving through.
If resistance of 1 component changes, the PD across all components changes. | | 37 |
| 16306719929 | What is the rule for PD in parallel circuits? | V1 = V2 = V3
PD is the same across al branches. All branches get full sourcce of PD - each charge can only pass down 1 branch so transfers all the energy supplied from source PD to component(s) on branch. | | 38 |
| 16306767449 | What is the rule for current in parallel circuits? | I = I1 = I2
Current is shared between branches.
Total current flowing round circuit = total of all currents through separate branches.
Total current going into a junction = total current leaving | | 39 |
| 16306802276 | What is the rule for resistance in parallel circuits? | Total R < R1 and total R < R2
Always less than the branch w. smallest resistance because charge has more than 1 route, only some of charge will flow along each branch. | | 40 |
| 16306881665 | What is power? | - The rate at which work is done
- Power of a component = how much energy it transfers / second
- Joules or kWh, kWh = amount of energy a device with a power of 1 kW (1000W) transfers in 1 hour - Bigger than a joule. | | 41 |
| 16307022342 | What's the difference between scalar and vector quantities? | - Scalar: only numbers e.g. speed, distance, mass, time etc
- Vector: directions as well e.g. velocity, displacement, force, acceleration etc | | 42 |
| 16307106532 | What do the part of d-t graph tell you? | - Gradient = speed (steeper - faster) - if graph curves draw tangent.
- Flat = stationary
- Curves = acceleration, steepening-speeding up, levelling off-slowing down | | 43 |
| 16307172420 | What do the part of v-t graph tell you? | - Gradient = acceleration (steeper= greater acceleration/deceleration)
- Flat = steady velocity
- Curve = changing acceleration
- Area under graph = distance travelled. | | 44 |
| 16307448194 | What is Newton's first law? | An object will stay stationary or at a constant velocity unless acted upon by an external force. | | 45 |
| 16307470385 | What is Newton's second law? | The force acting on an object is equal to its rate of change of momentum ( force = mass x acceleration) | | 46 |
| 16307668147 | What is Newton's third law? | When 2 objects interact, the forces they exert on each other are equal and opposite | | 47 |
| 16307496864 | What are the forces acting on a skydiver? | - Jumps out, only force is weight due to gravity - resultant force downwards, accelerating.
- As falls, experiences air resistance, but weight still greater to continues accelerating
- As velocity increases, air resistance also increases
- At certain point, air resistance balances weight - no resultant force, velocity is constant (TERMINAL VELOCITY)
- Opens parachute, SA increases, air resistance increases
- At certain point, air resistance will balance weight, resultant force = 0, velocity constant (LOWER TERMINAL VELOCITY) |  | 48 |
| 16307690441 | What is inertia? | - How difficult it is to change an object's velocity.
- Dependent on mass (larger mass, larger inertia)
- Use F=ma | | 49 |
| 16307785786 | What is the law of conservation of momentum? | In a collision when no other external forces act, momentum is conserved - total momentum after = total momentum before. | | 50 |
| 16307821115 | Compare elastic and inelastic collisions | - Elastic = total energy in the kinetic energy stores of object colliding is same before + after, it's conserved.
- Inelastic = some of energy in kinetic energy stores is transferred to other stores e.g. heating or sound. | | 51 |
| 16307881702 | What is work done? | When a force makes an object move, energy is transferred and work is done | | 52 |
| 16307913731 | Compare Elastic and plastic deformations | - Elastic = returns to original shape
- Plastic = doesn't (requires at least 2 forces) | | 53 |
| 16307960049 | What is Hooke's Law? | When a spring stretches, the extension of the spring is proportional to the force stretching it, provided the elastic limit of the spring is not exceeded. |  | 54 |
| 16308048242 | What is a moment? | - The turning effect of a force
- If a force acts on an object with a pivot, it causes the object to rotate around the pivot.
-Clockwise/Anticlockwise
- BALANCED objects obey principal of moments: total anticlockwise moments = total clockwise moments | | 55 |
| 16308112674 | What are levers? | - Force multipliers
- Transfer the turning effect of a force
- Increase distance from the pivot that force is applied, less input force needed to get same moment. | | 56 |
| 16308149850 | What are gears? | - Toothed wheels used to transfer forces from one part of a machine to another
- Used to change rotational speed or change rotational direction
- Use gear ratios to work out how speeds and moments change | | 57 |
| 16308213700 | What is the rule for pressure in liquids? | - Pressure in a fluid is transmitted equally in all directions and it causes a force at right-angles to any surface
- Caused by particles in liquid hitting sides of container
- Liquids are in-compressible - if a force is applied to one point, a net force will be transmitted to other points too | | 58 |
| 16308281559 | What are hydraulics? | - Force multipliers, use small force to produce bigger force.
- 2 pistons, second with bigger area, due to F = P x A, there is a larger force. |  | 59 |
| 16308331975 | What did JJ Thomson discover in 1897? | - Atoms not solid spheres
- Contain smaller -ve particles, electrons
- PLUM PUDDING MODEL |  | 60 |
| 16308358866 | What did Rutherford discover in 1909 with Geiger and Marsden? | - GOLD FOIL EXPERIMENT
- +ve alpha particles fired at gold: expected to pass through but some deflected back
- Tiny, +ve nucleus at enter surrounded by cloud of electrons, most of atom = empty space. |  | 61 |
| 16308411920 | What did scientists realise that made Rutherford's model incorrect? | That electrons in a cloud around the nucleus would be attracted causing atom to collapse | | 62 |
| 16308458841 | What did Neils Bohr discover? | - BOHR MODEL
- Electrons travel in fixed orbits, shells
- Each shell has fixed energy | | 63 |
| 16308507068 | What is the average size of an atom? | 1x10^-10 | | 64 |
| 16308540425 | What is specific heat capacity? How do you find a substance's SHC? | The amount of energy required to increase the temperature of 1kg of a substance by 1°C or 1 K.
For a liquid:
- Measure mass of substance
- Place into insulating container with thermometer and electric heater which is attached to joulemeter + lid
- Measure temperature, then turn on power
-When increased by 10° stop experiment + record joulemeter reading and increase in temp.
- Use equation to work out SHC
- Repeat 3 times | | 65 |
| 16308723503 | What is Specific latent heat? | The energy needed to change the state of 1kg of a substance without changing its temperature.
- Solid ⟷ Liquid = SLH of fusion
- Liquid ⟷ gas = SLH of vaporisation | | 66 |
| 16308829581 | What happens when a substance changes state? | - When melting/boiling, still adding energy, but used to break intermolecular bonds, not raise temp
- When a substance is condensing/freezing, bonds forming between particles, releases energy, temp does not go down. | | 67 |
| 16308917454 | Describe liquid pressure. | - An object in liquid experiences pressure due to particles in liquid.
- Pressure increases w. depth due to weight of column of liquid above
- Due to this, force pushing upwards on bottom of an object because of the liquid pressure is greater than force pushing down on top = UPTHRUST
- Upthrust acting = weight of fluid it's displaced. If equal to weight, will float. If less than weight, will sink
- To make float, must be less dense than liquid - will displace volume equal to its own weight before fully submerged.
- Liquids can't be compressed - density is the same everywhere | | 68 |
| 16309034514 | What does it mean when an object is in equilibrium? | | | 69 |
