PAGS Flashcards
1
Q
Method determining gravity
A
- Set up an electromagnet with a low voltage DC supply onto a clamp stand
- Connect one light gate and data logger as close to the electromagnet as possible, and one at 0.75m
- Turn on the electromagnet and attach a ball bearing
- Switch off the electromagnet and time how long it takes for the bearing to fall between the light gates
- Adjust the height of the lower light gate by moving it up 0.05m each time until it reached 0.25m
- find the mean values of t for each value of h
- plot a graph of 2h against t² so the gradient will equal g (s = ut+1/2at²)
2
Q
Investigating terminal velocity
A
- Wrap elastic bands around a cylinder of viscous liquid at set intervals measured by a ruler
- Drop a ball bearing into the tube and record the time it takes to reach each band
- Repeat the method to reduce the effect of random errors and use a strong magnet to remove the ball bearing from the bottom of the tube
- Calculate the average time taken for the ball to travel between each consecutive band
- Use the equation S=d/t to find the average velocity between each band
- Plot a graph of velocity against time
- Terminal velocity can be identified when the ball takes an equal amount of time to travel between the bands
3
Q
Investigating springs in series and parallel
A
- Set up a clamp stand attached to (n) springs in series/parallel attached to a 50g mass
- Record the initial length of the springs and the number of springs in series or parallel (n)
- Attach the mass and record the new length of the springs
- Repeat with different values of n
- Calculate the extension for each spring (new length-initial length)
- Find the spring constant of the combination (Force/extension of n)
- Total extension = sum of each individual springs extension
4
Q
Determining resistivity
A
- Measured the diameter across three points using a micro meter and calculate the mean diameter
- Set up a power supply ammeter and voltmeter in parallel to the wire
- Attach crocodile clips along the length of the wire at 10 cm using a meter rule
- Read and record the current and volts
- Switch the circuit on and off in between readings to prevent heating of components
- Repeat this process by increasing the length by 10 cm every time until 80cm
- Repeat the experiment to increase reliability and calculate the mean resistance using V = IR
- Calculate the cross-sectional area of the wire using A = πd²/4
- Plot a graph of resistance against length, the resistivity will be the gradient x cross-sectional area
5
Q
Determining internal resistance
A
- Set up a circuit with a battery, ammeter, variable resistor, switch and voltmeter in parallel to the battery
- Set up the variable resistor to its maximum value
- Close the switch and record the voltage from the volt meter and the current from the ammeter
- Open the switch between readings to prevent heating
- Repeat this method decrease the resistance of the variable resistor each time
- Put the equation ε= V + Ir into the form y=mx+c and plot a graph of V against I
- y-intercept = emf and the gradient = negative internal resistance
6
Q
Using non-ohmic devices as sensors
A
- Set up a circuit with a cell connected to an LDR and voltmeter in parallel to resistor
- Record the value of light intensity using a digital light sensor
- Record the voltage across the resistor for the light intensity
- Using a lamp with a varying intensity increase the light intensity slightly and record the new value recorded by the sensor and record the voltage across the resistor
- Repeat this process until light intensity cannot be increased any further
- Plot a graph of voltage across the resistor and light intensity and draw a line of best fit