PAGS Flashcards
Determine acceleration of free fall
Determine terminal velocity in fluids
Investigate force-extension characteristics
- Apparatus- attach spring to clamp securely and metre ruler using set square to make it straight
- On ruler mark bottom of spring for original length
- Hang mass hanger and record new length against mass
- Calculate extension, new-original
Repeat until spring has become permanently deformed - Repeat for rubber band and polyethene strip
- y=mx+c -> F=kx for straight only
*Read ruler at eye level
*Make sure material is stationary b4 reading
*Repeat and calculate mean
Determine young modulus
- Measure diameter of wire with micrometer or digital callipers. Atleast 3 readings and average
- Make sure wire is taught
- Measure length of wire and mark point on wire and metre ruler and record on ruler.
- Add 100g onto mass hanger
- Record the new length on the metre ruler. And record
- Repeat by adding mass atleast 5-10x and record in table
- Calculate extension by new-original
- Plot graph of force against extension and line of best fit
Calculate gradient - Cross sec area= pied2/4
- YM= gradient x l / A
- remove load and check wire returns to pre length b4 new reading to make sure it hasn’t passed elastic limit
- measure diameter in several places
- parallax error from ruler
Determining Planck constant
- Set up circuit, connect ammeter, variable resistor and LED in series and voltmeter parallel to LED
- Slowly increase voltage by changing resistance until LED just begins to emit light
- Record this threshold voltage
- Repeats for each coloured LED
- Record in table with wavelength that you would find in box of LED
- eV = hc/ wl
- Plot graph Vo against 1/wl and gradient = hc/e
- h = gradient x e/c
*be in dark room
Percentage error
Experimental-accepted/accepted x 100
Determine internal resistance
• circuit with cell in series with ammeter and variable resistor
• voltmeter across cell
• measure current and pd across cell
• change resistance of variable resistor to get multiple readings
• plot graph V against I
• gradient = -r
• E = V + Ir , V = -Ir + E
• Repeat and take mean
- add switch and open between readings to avoid heating up r changing
- use new cells
Investigate potential divider circuits LDR
IV: light intensity
DV: pd
CV: emf
•circuit with LDR and resistor in series
• voltmeter across resistor
• record V across resistor for this light intensity
• using lamp with dimmer switch, increase light intensity and record new value on sensor
• record V again
• Repeat until light intensity can’t increase further
• Plot graph of pd against light intensity and draw line of best fit
• resistance decrease as light intensity increases
• doesn’t obey ohms law
• pd provided by cell is shared by resistor and non ohmic device
Investigating electrical characteristics of components
• circuit with cell in series with variable resistor, component and ammeter
• voltmeter across component
• vary V across component by changing variable R
~ wide range of readings
~ increase V in steps of 0.5V
• Record current and repeat to get mean
•Repeat
• Reverse terminals to take reading of -V and -I
• Replaces component, fixed resistor, filament lamp and diode
• Repeat for each
• Plot graph of I against V
• If straight line ohmic conductor and obeys ohms law
• If curves non ohmic ( lamp and diode
- switch off circuit in between readings to prevent heating
- could be slightly inaccurate as as voltmeter and ammeter has some resistance
Determining resistivity of metal
• Wire taped to ruler with one end of circuit attached to wire where ruler reads 0
• Ammeter and cell connected in series and voltmeter across test wire
• measure diameter of test wire with micrometer
~ 5-10x randomly along wire then mean
• attach flying lead to wire at 0.25m
• then set power supply and check that it’s through the wire on voltmeter
•Record current, then switch of current
• vary distance between fixed end of wire and flying lead until reached full length of wire (8-10 readings)
• record I for each length multiple times to get average
• calculate average resistance for length, R= V/I
• R= pL/A
•Plot graph wire length against resistance
• Line of best fit,
• Cross sect area from diameter
• p= gradient x area
Potential divider circuit thermistor
IV: Temp
DV: pd
CV: emf
• Thermistor and resistor in series
• voltmeter across resitor
•Place thermistor in beaker filled with boiling water with kettle
• record pd across resistor every decrease in 5’C
• repeat measurements for pd
• wide range of readings
Temp of thermistor assumed to be same temp of water
