Core Practicals Flashcards
(128 cards)
1
Q
What is the aim of CP01?
A
To determine the acceleration due to gravity (g) using a free-fall method.
2
Q
What equipment is used in CP01? (7)
A
Light gates, electromagnet, steel ball bearing, timer, ruler, release mechanism, trapdoor.
3
Q
What is the equation used to calculate g in CP01?
A
s = 1/2gt² -> g = 2s/t²
4
Q
What variables are measured in CP01? (2)
A
Distance fallen (s), time taken (t).
5
Q
How can you reduce errors in CP01?
A
Use electronic timing with light gates to minimize human reaction time error.
6
Q
What are the major sources of uncertainty in CP01? (3)
A
Timing errors, parallax error in distance measurement, air resistance.
7
Q
How do you analyse CP01 data graphically?
A
Plot s (y-axis) against t² (x-axis); the gradient gives 1/2g
8
Q
What is the aim of CP02?
A
To determine the resistivity (ρ) of a wire.
9
Q
What is the equation for resistivity?
A
ρ = RA/L, where R is resistance, A is cross-sectional area, L is length.
10
Q
What instruments are used in CP02? (7)
A
Micrometer, ammeter, voltmeter, ruler, wire (e.g., nichrome), power supply, crocodile clips.
11
Q
How is resistance determined in CP02?
A
Measure V and I, then calculate R=V/I
12
Q
How do you find the cross-sectional area (A) of the wire?
A
Measure diameter with a micrometer and calculate A = πd²/4
13
Q
What graph do you plot in CP02?
A
V (y-axis) vs. I (x-axis); gradient gives resistance.
14
Q
How do you calculate resistivity from your measurements?
A
Use ρ = RA/L with average values for R, A, and L.
15
Q
How can you reduce uncertainty in CP02? (3)
A
Measure diameter at several points; keep wire straight; avoid heating wire during measurements.
16
Q
What is the aim of CP03?
A
To determine the EMF and internal resistance of a power source.
17
Q
What is the equation relating V, EMF, and internal resistance?
A
ε = V + Ir
18
Q
What is plotted in CP03 and what does it represent?
A
V (y-axis) vs. I (x-axis); y-intercept = EMF ε, gradient = -r.
19
Q
What equipment is used in CP03? (5)
A
Power supply or cell, variable resistor, ammeter, voltmeter, connecting wires.
20
Q
How do you vary current in CP03?
A
Use a variable resistor (rheostat) to change the load resistance.
21
Q
Why should you switch off the circuit between readings in CP03?
A
To prevent heating the cell, which would change its internal resistance.
22
Q
How can you reduce error in CP03? (3)
A
Use precise digital meters; take multiple readings; allow the cell to rest between measurements.
23
Q
What is the aim of CP04?
A
To determine the viscosity of a fluid using Stokes’ Law.
24
Q
What is Stokes’ Law?
A
F = 6πηrv, where η is the viscosity, r is radius, v is terminal velocity.
25
What equipment is used in CP04? (5)
Viscous fluid (e.g., glycerol), ball bearings, stopwatch, ruler or marked cylinder, thermometer.
26
How do you find terminal velocity in CP04?
Measure time taken for ball to fall a set distance once it reaches constant speed.
27
What assumptions are made when applying Stokes' Law? (4)
Ball is small, flow is laminar, ball reaches terminal velocity quickly, fluid is Newtonian.
28
How do you calculate viscosity (η) in CP04?
Rearranged Stokes’ Law: η = 2(ρₛ - ρₗ)gr²/9v
29
How do you ensure accuracy in CP04? (3)
Use balls of known radius; measure temperature (affects viscosity); use large cylinder to reduce wall effects.
30
What graph can be plotted for CP04?
Plot v vs. r² or use multiple ball sizes to find η from the gradient.
31
What is the aim of CP05?
To determine the Young’s Modulus of a wire.
32
What is the equation for Young’s Modulus?
E = stress/strain = FL/AΔL
33
What measurements are needed in CP05? (4)
Force (F), original length (L), extension (ΔL), and cross-sectional area (A).
34
How do you measure extension in CP05?
Use a ruler or a travelling microscope to measure the increase in length from a fixed point.
35
How is cross-sectional area (A) calculated?
A = πd²/4 , where d is the diameter measured using a micrometer.
36
What graph do you plot in CP05?
Stress (y-axis) vs. strain (x-axis); gradient gives Young’s Modulus.
37
What are some sources of error in CP05?
Parallax error in measuring extension, slip/stretch in wire, inaccurate force calibration.
38
How do you reduce uncertainty in CP05?
Use small increments of load, ensure wire is taut before measurements, measure diameter at multiple points.
39
What is the aim of CP06?
To determine the speed of sound in air using a dual-input oscilloscope.
40
What is the key equation used in CP06?
v = fλ, where v is the speed, f is the frequency, and lambda is the wavelength.
41
What equipment is used in CP06? (5)
Signal generator, loudspeaker, one microphone, oscilloscope, ruler/tape measure.
42
How is wavelength determined in CP06?
Move microphone to find the distance between points where the signals are in phase → this is one wavelength.
43
How is frequency known in CP06?
It’s set by the signal generator.
44
How do you improve accuracy in CP06?
Use clear phase alignment on the oscilloscope, repeat measurements, and average wavelength.
45
How do you use the graph to determine λ in CP06?
Plot microphone separation vs. number of wavelengths; gradient gives λ.
46
What assumptions are made in CP06? (2)
Air is still and at constant temperature; signal remains coherent and sinusoidal.
47
What is the aim of CP07?
To investigate how frequency depends on length, tension, and mass per unit length of a vibrating string.
48
What is the fundamental frequency equation for a string?
f = 1/2L x √T/μ
49
What factors affect frequency in CP07? (3)
Length (L), tension (T), and mass per unit length (μ).
50
What equipment is used in CP07? (6)
Signal generator, vibration transducer, string or wire, pulley, masses, metre rule.
51
How can you vary tension (T) in CP07?
Change the hanging mass over the pulley.
52
How do you measure frequency in CP07?
Set it on the signal generator or measure with an oscilloscope.
53
How do you verify relationships in CP07?
Plot graphs:
* f vs. 1/2L → linear
* f vs. √ T → linear
* $f$ vs. 1/√ μ → linear
54
What are sources of error in CP07? (3)
Difficulty in identifying resonant frequencies, damping of vibrations, imprecise length measurements.
55
What is the aim of CP08?
To determine the wavelength of a laser light using a diffraction grating.
56
What is the diffraction equation used?
nλ = dsinθ, where:
* n = order number
* λ = wavelength
* d = slit spacing
* θ = angle from central maximum
57
How do you calculate grating spacing d?
d = 1/lines per metre
58
What measurements are taken in CP08? (2)
Distance from grating to screen (D), and fringe separation from central maximum to each order (x).
59
How do you calculate angle θ?
tanθ = x/D, then find sinθ
60
What graph can be plotted in CP08?
sinθ (y-axis) vs. order n (x-axis); gradient = λ/n
61
How can you reduce uncertainty in CP08?
Measure across multiple fringes and average; use a large screen distance; ensure laser is perpendicular.
62
What are safety precautions in CP08?
Do not look directly into the laser; avoid reflective surfaces.
63
What is the aim of CP09?
To investigate how force relates to the rate of change of momentum during a collision.
64
What key principle is tested in CP09?
Newton’s Second Law: F = Δp/Δt
65
What equipment is used in CP09? (7)
* Light gates
* Data logger
* Dynamic trolley
* Motion sensor
* Ramp or track
* Mass pieces
* Force sensor
66
What is the formula for momentum?
p = mv
67
How is impulse defined?
Impulse = Change in momentum = FΔt
68
How do light gates help in CP09?
They measure initial and final velocities, allowing calculation of momentum change.
69
What graph is used in CP09?
Force (y-axis) vs. time (x-axis); area under graph = impulse = Δp
70
How do you reduce error in CP09? (4)
* Use smooth track
* Align sensors carefully
* Take multiple repeats
* Zero equipment before use
71
What is the aim of CP10?
To analyse elastic and inelastic collisions using video or motion tracking software.
72
What law is primarily tested in CP10?
Conservation of momentum.
73
What is conserved in elastic collisions?
Both momentum and kinetic energy.
74
What is conserved in inelastic collisions?
Only momentum (kinetic energy is not conserved).
75
What equipment is used in CP10? (4)
* Small spheres (e.g. ball bearings)
* Flat surface or air track
* Video camera
* Software for motion tracking
76
How is momentum calculated in CP10?
p = mv; use measured mass and velocity from video tracking.
77
What graph can be plotted in CP10?
* Total momentum before vs. after collision
* Kinetic energy before vs. after
78
What are sources of error in CP10? (4)
* Friction
* Measurement error from video resolution
* Misalignment of tracking
* Parallax error
79
How to reduce error in CP10? (3)
* Calibrate video scale accurately
* Ensure flat surface
* Use high-speed camera
80
What is the aim of CP11?
To observe and analyse how voltage changes across a capacitor during charging and discharging.
81
What is the key exponential equation for discharging a capacitor?
V = V₀e⁻ᵗ/ᴿᶜ
82
What does the time constant represent?
τ = RC; the time taken for V to fall to 1/e (~37%) of its original value.
83
What equipment is used in CP11? (6)
* Capacitor
* Resistor
* Power supply
* Switch
* Voltmeter or data logger
* Stopwatch
84
What graph is plotted in CP11?
* V vs. t for charging/discharging
* ln V vs. t (linear: gradient = -1/RC)
85
How can you determine the time constant from a graph?
From ln V vs. t graph: gradient = -1/RC → RC = -1/gradient
86
How to reduce error in CP11? (3)
* Use digital data logger for more accurate readings
* Ensure good connections
* Use consistent starting voltages
87
What happens to voltage across capacitor during charging?
Increases from 0 to maximum asymptotically.
88
What happens during discharging?
Voltage decreases from maximum to 0 exponentially.
89
What is the aim of CP12?
To calibrate a thermistor as a temperature sensor in a potential divider circuit.
90
What is a thermistor?
A temperature-dependent resistor; in an NTC thermistor, resistance decreases as temperature increases.
91
What is a potential divider?
A circuit that divides voltage between two components based on their resistances.
92
What equipment is used in CP12? (7)
* Thermistor
* Fixed resistor
* Power supply
* Voltmeter
* Thermometer
* Water bath or ice bath
* Beaker
93
What graph is plotted in CP12?
Output voltage (V) vs. temperature (°C); typically a nonlinear decreasing curve.
94
What does the graph show about sensitivity?
Small changes in temperature cause larger voltage changes at lower temperatures.
95
How to calibrate the thermistor?
Record voltage across thermistor at known temperatures and plot graph.
96
How can this circuit act as a thermostat?
When voltage reaches a set level (corresponding to a temperature), it can trigger a relay or transistor switch.
97
How to reduce error in CP12? (3)
* Stir water for uniform temperature
* Allow thermistor to reach thermal equilibrium
* Use a digital thermometer
98
What is the aim of CP13?
To determine the specific latent heat of fusion (ice) or vaporisation (water).
99
What is the equation for latent heat?
Q = mL, where Q is energy,,m is mass, L is specific latent heat.
100
How is energy calculated in this practical?
Q = IVt, where I = current, V = voltage, t = time.
101
How do you find L using the energy equation?
Rearranged: L = IVt/m
102
What equipment is used for determining latent heat of vaporisation? (8)
Electrical heater, beaker of water, thermometer, power supply, ammeter, voltmeter, stopwatch, balance.
103
What must you measure for latent heat of vaporisation? (4)
Mass of water evaporated (Δm), current, voltage, time.
104
What are sources of error in CP13? (3)
Heat loss to surroundings, inaccurate mass readings, water splashing during boiling.
105
How can heat loss be reduced? (3)
Use insulation, a lid, and conduct experiment quickly.
106
What is the aim of CP14?
To verify Boyle’s Law: pV = constant
107
What is Boyle’s Law?
Pressure is inversely proportional to volume at constant temperature.
108
What is the key equation for CP14?
p ∝ 1/V
109
What apparatus is used in CP14? (3)
Boyle’s Law apparatus (sealed syringe or oil column), pressure sensor, ruler or volume scale.
110
What graph is plotted for CP14?
Pressure (y-axis) vs. 1/V (x-axis); straight line through the origin confirms Boyle's Law.
111
What are key conditions for CP14 to be valid?
Temperature must remain constant throughout (isothermal process).
112
What are common errors in CP14? (3)
Leaks in apparatus, parallax in reading volume, temperature changes.
113
How can you minimise temperature changes? (2)
Wait between readings, avoid rapid compression or expansion.
114
What is the aim of CP15?
To investigate how gamma radiation intensity decreases with increasing lead thickness.
115
What is the key equation for gamma absorption?
I = I₀e⁻μˣ, where:
* I = transmitted intensity
* I₀ = initial intensity
* μ = absorption coefficient
* x = thickness of absorber
116
What graph is plotted in CP15?
ln I (y-axis) vs. $x$ (x-axis); gradient = -μ
117
What equipment is used in CP15? (6)
Geiger-Müller tube, gamma source (e.g., Co-60), lead sheets, counter, ruler, stopwatch.
118
Why is it important to measure background radiation?
To subtract from each count, giving accurate net radiation.
119
What precautions are taken for safety in CP15? (4)
Use tongs, lead shielding, minimise exposure, never point source at anyone.
120
What are sources of error in CP15? (2)
Random nature of radiation (use long count times), background count fluctuation.
121
What is the aim of CP16?
To determine an unknown mass using the resonance frequency of a vibrating system.
122
What is the relationship between frequency and mass for a spring-mass system?
f = 1/2π x √ k/m
123
What is the rearranged equation to find mass?
m = k/(2πf)²
124
What is meant by resonance in this context?
The frequency at which the system naturally oscillates with the greatest amplitude.
125
What equipment is used in CP16? (6)
Signal generator, vibration generator, spring or elastic cord, slotted masses, balance, meter ruler.
126
How do you determine the spring constant (k)?
Use Hooke’s Law: k = F/x, where F = mg, and x is extension.
127
What graph can be plotted to help find mass?
f² (y-axis) vs. 1/m (x-axis); gradient = k/4π²
128
What are sources of error in CP16? (4)
Inaccurate frequency measurement, air resistance, friction, imprecise mass values.
