Flashcards in Core Practicals Deck (56)

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1

## Determine the mass of a free falling object method.

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Drop a sphere from rest and record time taken to fall through trap door or to pass through light gates.

Repeat measurements and take mean value.\Record height dropped from.

Vary height dropped from.

Plot t^2 on y-axis and h on x-axis.

Gradient 2/g

Or plot v^2 against h and gradient 2g.

2

## Determine the mass of a free falling object risks.

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Clamp stand could fall and injure.

Metal ball used could be heavy and injure, must be cushioned.

Container to catch ball bearing and prevent trip hazard.

If using electromagnet tom release, care should be taken with wires to prevent short circuits.

3

## Determine the mass of a free falling object uncertainties.

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Resistive forces.

Zero error – systematic error.

4

## Determine the electrical resistivity of a material method.

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Crocodile clip on wire at “zero” end of the ruler.

Use a 4mm plug free end to make contact with wire at different lengths.

Record R and length.

Measure diameter.

Plot R against length.

Gradient is resistivity over CSA.

5

## Determine the electrical resistivity of a material equation.

### R = ρl/A

6

## Determine the electrical resistivity of a material risks.

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Although low voltages are used, care should be taken with wires to prevent short circuits.

Heat of wire – can be reduced by adding a resistor in series.

7

## Determine the electrical resistivity of a material uncertainties.

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Ruler and micrometer, eye level and set square to avoid parallax error.

Check ammeter and voltmeter for zero error.

8

## Determine the emf and internal resistance of an electric cell method.

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Cell and variable resistor.

Vary resistance and measure current and pd across resistor.

Plot V against I

Magnitude of the gradient gives r

y-intercept gives emf of the cell.

9

## Determine the emf and internal resistance of an electric cell equation.

### ε = V + Ir

10

## Determine the emf and internal resistance of an electric cell risks.

### Although low voltages are used, care should be taken with wiring to prevent short circuits.

11

## Determine the emf and internal resistance of an electric cell uncertainty.

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Zero error on ammeter and voltmeter.

Heat increases resistance so break circuit when not measuring.

12

## Use free falling ball to determine the viscosity of a liquid method.

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Weigh balls, measure radius and calculate the density of the balls.

Three rubber bands around tube.

Highest at terminal velocity.

Two intervals for measuring terminal velocity

Adjust if not suitable distance apart.

Repeat at least three times for each diameter of ball.

13

## Use free falling ball to determine the viscosity of a liquid risks.

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Marbles/ball bearings to be kept in container to prevent slipping.

Liquids must be wiped up if spilled immediately.

Glassware.

Stable container must be used.

14

## Determine the Young modulus of a material method.

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Fix bench pulley at the end of a bench and G-clamp wire at the opposite end of bench between wooden blocks.

Lay wire over pulley and attach a small mass so taught.

Using a micrometer measure diameter of wire in at least 3 places and take average.

Lay meter ruler near pulley and attach marker to wire. Use set square to measure distance and avoid parallax error.

Measure length of wire between clamp and mark.

Add masses to the wire and measure extension.

If creep takes place then elastic limit has been exceeded.

15

## Determine the Young modulus of a material equations.

### E = σ/ε or E = Fx/AΔx

16

## Determine the Young modulus of a material risks.

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Goggles worn as wire under high tension.

Cardboard bridge over wire.

Cushion under weights do not put feet under weights.

17

## Determine the Young modulus of a material uncertainty.

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Large uncertainty in measurement of extension.

Longer wire reduces uncertainty.

18

## Determine the speed of sound in air using a 2- beam oscilloscope, signal generator, speaker and microphone method.

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Place microphone about 50cm away from the speaker and set signal generator to 4kHz.

Adjust the oscilloscope to show 3 cycles on display.

Connect the signal generator to the oscilloscope.

Adjust the traces so the peak of one trace touches the trough of another.

Measure distance from speaker to the microphone then move until one complete wave cycle on the oscilloscope and record the change in distance.

Repeat and record the mean distance.

Use one of the traces to determine the frequency of wave.

Using signal generator halve frequency and repeat with distances greater than 1m.

Using data calculate speed at each frequency and take mean speed at end.

19

## Determine the speed of sound in air using a 2- beam oscilloscope, signal generator, speaker and microphone equation.

### v = fλ and f = 1/T

20

## Determine the speed of sound in air using a 2- beam oscilloscope, signal generator, speaker and microphone uncertainty.

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Uncertainty in measuring distance with ruler.

Uncertainty in measuring T on oscilloscope.

21

## Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire method.

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Attach one end of the string to the vibration generator and run the other end over a pulley with a mass hanger attached.

Add masses to the hanger until there is 100g attached.

Set the vibration generator running and airy the vibrating length by moving the generator until resonance is observed.

Vary either length or tension and measure resonant frequencies.

Plot graph to find mass per unit length.

22

## Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire equation.

### v = √(T/μ)

23

## Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire risks.

### Hanging masses, cushion floor and mark area where you can't stand.

24

## Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire uncertainties.

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Measuring length of string.

Measuring tension using masses and top-pan balance.

25

## Determine the wavelength of light from a laser or other light source using a diffraction grating method.

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Place laser 4m from wall.

Place diffraction grating in front of laser so the beam and the wall are perpendicular.

Measure distance from grating to the wall.

Identify zero order maxima and measure distance of first order by measuring distance between and dividing by two.

Measure distance for increasing orders of maxima and repeat for different diffraction gratings.

26

## Determine the wavelength of light from a laser or other light source using a diffraction grating equation.

### nλ =dsin θ

27

## Determine the wavelength of light from a laser or other light source using a diffraction grating risks.

### Laser should be marked, safety goggles should be worn.

28

## Determine the wavelength of light from a laser or other light source using a diffraction grating uncertainty.

### Distances with metre rule.

29

## Use ICT to analyse collisions between small spheres method.

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Measure diameter of spheres.

Set up camera to record collision in 2 dimensions from above.

Place graph paper underneath the camera in the frame that the collision will take place on.

Start a collision between a sphere by setting it rolling down slight slope towards second sphere.

Repeat varying collision angle.

Use tracker and the velocity overlay to analyse velocities, add mass of spheres to tracker for momentum.

Compare momentum before and after in all directions for conservation of momentum.

30