Practical physics - Experiments

State what apparatus can be used to produce a changing current/voltage draw their symbol

• a.c power supply

• signal generator

State what apparatus can be used to measure changing voltage/current

• Oscilloscope

State what apparatus can be used to measure the frequency of a signal

• Oscilloscope

Describe how the frequency of an oscilloscope can be found

• Period T = time-base * horizontal distance

• frequency = 1 / T

Describe how voltage/current can be found from an oscilloscope

• V/Current = y-gain * vertical distance

Describe how resistance can be measured

• Use an ohmmeter

• Measure current in resistor and p.d across resistor then use R = V / I

Describe how the distance between two coils can be kept constant

• clamp/fix the coils to bench

Describe how a light gates can measure t

• Measures the time the infrared sensor has been blocked

State how the time taken for something to occur can be measured, draw a diagram of these

• Stop-watch, placed in frame of video camera and measurement

• Two Light gates, connected to a data logger

Describe how light gates can measure the time taken for an object to move a distance

• Use two light gates, one at the beginning and one at the end

• The data logger then measures the time difference between the break in the first light gate and the second light gate

Describe how light gates can measure the velocity of a moving object

• Use a single light gate connected to a data logger

• Attach a card of known length to the object

• Measure the time the infrared beam was broken for

• length of card / time taken = velocity

Describe how light gates can measure the acceleration of a moving object

• Use two light gates connected to a data logger

• Attach a card to the object of known length

• Change the setting on the data logger to measure acceleration

• Data logger provides value for acceleration

State what apparatus can be used to measure mass, draw their diagrams

• Digital balance

• Top-pan balance

State what apparatus can be used to measure angles

• Protractor

• Rule, using trigonometry

Describe how frequency can be measured from an oscillating object

• Measure the time taken for n rotations, if too fast, record a video and play frame by frame with a time stamp

• Period T = n / time taken

• frequency = 1 / T

State the apparatus required to hold an oscillating object in place

• Boss stand clamp, put a needle/rod through ihole in object and hold rod in place with clamp

Describe how to measure the capacitance of a capacitor

• Measure the current flowing through a resistor during the discharge of the capacitor

• C = It / V

Describe how to measure the thickness of a length

• Using vernier calipers

• Using a micrommeter screw gauge

Describe how B is measured

• A hall probe

• Adjust the probe until maximum value

• Measure B in one direction then in the opposite direction and average

State what apparatus is needed to keep an object at an angle

• A stand