Practicals Flashcards
(18 cards)
pg. 31
Youngs double slit experiment
explain
- use two coherent monochromatic light sources or shine a laser through two slits.
- the slits have to be the same size as the wavelength of the laser so that it can fully diffract
- you get a pattern of light and dark fringes depending on whether constructive or destructive interference is taking place.
what are the dangers or risks of the youngs double slit
- don’t shine laser towards a person
- wear laser safety goggles
- avoid shining at reflective surfaces
- have warning sign on display
how can the double slit experiment be used on an microwave
- replace laser and slits with two microwave transmitter cones attached to the same signal generator
- replace the screen with a microwave receiver probe
- if you move probe along the path of the green arrow youll get an alternating pattern of strong and weak signals like the dark and bright fringes on screen
why is the light passing a diffraction grating get really sharp patterns
because there’s so many beams reinforcing the pattern
this gives more accurate measurements
explain the free fall experiment
- measure the height from the bottom of the ball bearing to the trapdoor
- flick the switch to simultaneously start the timer and disconnect the electromagnet
- the ball bearing falls, knocking the trapdoor down and breaking the circuit which stops the timer, record T
- repeat this experiment 3 times and find the average time taken to fall from the same height
- repeat experiment from several heights
what’s the most significant source of error in the free fall experiment
the measurement o the height is sung a ruler has an uncertainty
what’s the gradient of a free fall diagram
g= 2 x displacement/ time^2
what’s newton’s first law
velocity of an object will not change unless a resultant force acts on it
what’s newton’s second law
acceleration is proportional to force
f=ma
what did galileo say
all objects fall at the same rate when air resistance is ignored
what’s newton’s third law
for each force has a equal and opposite reaction with the same type of force
what affects the vehicles max speed
increasing driving force
reducing frictional force
what’s the principle of conservation of energy
energy can’t be created or destroyed
energy can be transferred from one form to another but the total amount of energy in a closed system won’t change
explain the practical of young modulus
- find the cross sectional area by using a micrometer to measure the diameter of the waiter in several places and take an average of your measurements assuming that the cross section is circular
- clamp the wire to the bench so you can hang weights off one end of it
start with small weights to straighten it wire but don’t use this in ur final weight calculations - measure the distance between the fixed end of the wire and the marker, this is ur unstretched length
- increase the weight in steps, recording the marker reading each time you add weight and find extension
- use ur results from experiment to calculate stress and strain and plot it on a stress strain graph
explain the resistivity practical
get the crosssectional area and yk how to do that
- the test wire should be clamped to a ruler with the circuit attached to the wire where the ruler reads zero
- attach the flying lead to the test wire, the lead is just a wire with a crocodile clip
- record the length of the test wire connected in the circuit, and the voltmeter and ammeter readings
- use your readings to calculate the resistance and of the length of the wire
- repeat to get average resistance for length
- repeat with diff lengths
- plot your results on a graph resistance over length and draw line of best fit
- the resistivity of a material depends on its temperature, so you can only find the resistivity of a material at certain temp
what’s a random error that can occur when calculating resistivity and how to fix
the temp of the wire increasing cuz of the current
fix it by keeping a low current and trying to keep the temperature constant
explain the experiment on internal resistance
use a variable resistor to change the resistance in the circuit
measure the current in the circuit with ammeter
measure pd with voltmeter
take multiple readings and average to improve the accuracy of the experiment
plot V/I
