Paper 1 Required Practicals Flashcards
(23 cards)
Method for stationary wave on a string
-Set up apparatus with stand, vibration generator, string, moveable bridge, pulley, masses, counterweight, metre ruler
-Measure mass of string with balance
-Start at length 1m and change frequency until first harmonic, record f
-Change length by 0.1m and repeat, doing 5 lengths
-Repeat and find mean f for each l, plot f against 1/l to find wave speed, v
Safety measure for stationary wave on a string
Stand could topple and cause injury so put counterweight on it
Sources of error for stationary wave on a string
Vibration generator may not be at right f, use oscilloscope to verify
Signal generator may not be at right f, leave for 20 mins to stabilise
Method for Young’s double slit
-Set up apparatus with laser, double slit and screen in darkened room
-Measure D to be 0.5m, measure multiple fringes’ width and divide to find mean w
-Increase D by 0.1m and repeat, 5 lengths
-Repeat each length twice, and plot mean w against D to find λ
Safety measure for Young’s double slit and diffraction grating
Lasers could shine in someone’s eye, so tilt reflective surface’s down, don’t do at eye level, don’t point at people
Sources of error for Young’s double slit and diffraction grating
Screen and double slit could be misaligned so use set square
Fringe width could be uneven so find mean
Method for diffraction grating
-Set up apparatus with laser, diffraction grating and screen in darkened room
-Measure D to be 1.0m and measure distance from 0th order to other orders and find mean
-Calculate d by doing 1/ number of slits written on grating
-Find angles, calculate λ and find mean
Method for g by freefall
-Set up apparatus with stand, clamp, electromagnet, steel ball, light gates, counterweight
-Make h, distance between light gates, 0.5m
-Set stopwatch to zero, turn off magnet and record time t for fall
-Reduce h by 0.05m by moving lower light gate up, repeat and find mean
-Plot graph of 2h/t against t, gradient is g
Safety measure for g by freefall
Stand could topple and cause injury so use counterweight
Ball could bounce onto someone so cushion it
Sources of error for g by freefall
Distance between first light gate and start could change so keep measuring
Air resistance so use a dense ball
Use set square or clamp to reduce parallax error in measuring h
Method for Young’s modulus
-Set up apparatus with 2 long steel wires, the main and Vernier scale, metre ruler, masses
-Measure initial length of test wire using metre ruler
-Add 1kg mass so wires are taut and record l
-Add 1kg more and calculate e each time, find mean e for each m
-Use micrometer to calculate A of wires by finding mean d
-Plot F against e and find gradient to calculate E
Safety for Young’s modulus
Wire will stretch and could break and go in someone’s eye so wear safety goggles
Masses could fall if wire break so cushion below them
Sources of error for Young’s modulus
Comparison wire compensates for other sagging and thermal expansion
Percentage uncertainty could be large so have large initial length
Method for resistivity of a wire
-Set up apparatus with power supply, ammeter in series, voltmeter in parallel, a constantan wire and two crocodile clips
-Use a micrometer to calculate A of wire
-Measure l as 1.00m with clips and metre ruler and calculate R using R=V/I
-Increase l by 0.1m and repeat, find mean R for each length
-Plot mean R against length and find ρ
Safety for resistivity of a wire
Wire could heat up and cause burns if touched, disconnect crocodile clips between readings
If wire is tight it could snap so wear goggles
Sources of error for resistivity of a wire
Wire could heat up and resistance could increase so disconnect clips between readings
Wire should be kept as straight as possible and without kinks so length is as accurate as possible
Method for internal resistance and emf
-Set up apparatus with cell, voltmeter in parallel to it, switch, ammeter and variable resistor
-With switch open record initial V
-Set variable resistor to max value, close switch and record V and I
-Decrease resistance and record V and I for each over widest possible range
-Plot V against I which will give straight line with equation V = -rI + ε
Safety for internal resistance and emf
Wires could get hot and cause burns so another resistor could be used, also to decrease high currents
Sources of error for internal resistance and emf
Wires could get hot and increase resistance in circuit so open switch between readings
Old cell’s emf could change in experiment so use a new cell
Method for mass spring and simple pendulum SHM
-Set up apparatus with spring or string, masses or bob, stand and clamp, pin and blue tack (marker) at equ point
-Add a mass or increase length, pull and release
-Time the time taken for 10 complete oscillations and find mean
-Increase mass or length and repeat, find a mean T for each mass or length
-Plot T^2 against m or T^2 against l
Safety for mass spring SHM
Suspended masses could fall and hurt someone so don’t pull too far and use light weight
Sources of error for mass spring SHM
Make sure oscillates only downwards
Place fiducial marker at centre of oscillation to give a clear point to time from
Time many oscillations to get more accurate mean
Sources of error for simple pendulum SHM
Have to measure to centre of mass so use a small bob
Don’t release from a large angle
