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# Experiments

### Physics Experiments

Experiment | things to remember |
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Constant velocity of a metal rider on an air track | *level air track so rider travels with constant velocity *attach card of length l *record time card breaks light gate for t *calculate velocity using v=l/t |

Measure constant acceleration of a rider on an air track | *attach card of length l *connect newtons to rider *measure t1 on first light gate and t2 on the second *record distance s between two light gates *calculate acceleration by v^2=u^2+2as i.e: a=v^2-u^2/2s |

Measure 'g' acceleration due to gravity using free fall apparatus and a scalar timer *GRAPH | *measure distance s from bottom of ball to vibration plate *measure range of values for t and pick smallest *use variation of s=ut+1/2at^2: a=g and u=0, g=2s/t^2 *g= 2(slope of graph) |

To show that a∝f *GRAPH | *all but one newtons on rider, other one on pan connected, move one each time *record: :length of card l :times t1 and t2 :the distance between the light gates s :the mass of the newtons on the pan m *u=l/t1 and v=l/t2 *a=v^2-u^2/2s *f=m(kg)x9.8 |

Verify the principle of conservation of momentum | *one light gate before second rider *one light gate after second rider *record mass of rider&card and other rider (m1 & m2) *u1=l/t1 u2=0 *v1=v2=l/t2 *m1u1 + m2u2 = v(m1+m2) |

To verify Boyle's law i.e. p∝1/v *GRAPH | *Boyle's Law apparatus *pump air into inlet of oil reservoir until pressure is at max *wait for temp to settle *record :volume of air column :pressure reading from gauge *increase the pressure *record range of values |

The Laws of equilibrium for a set of co-planar forces | *find weight of metre stick (mg) *use string to find centre of gravity and record point *hang weights and suspend from newton spring balances *adjust until horizontal equilibrium *get sum of clockwise and anticlockwise moments (=0) *resultant force=0 |

Relationship between period and length & calculate 'g' *GRAPH | *length as long as possible *swing: with angle<5° :in one plane only *record :length l :the time T for 50 oscillations *dec. length and record range *calculate :T1 time for 1 oscillation and T^2 :l/T^2, all values should be approx. same g=4π^2(l/T^2) |

Plot the calibration curve of a themometer *GRAPH | *ungraduated thermometer *mercury thermometer *place both thermometers in :ice :vaious temps of heating water :boiling water *record temp. against length |

Measure the Specific Heat Capacity of water: Electrical Method | *find mass of calorimeter mc and mass of water mw *measure temp. of cold water & calorimeter Θ1 *switch on joulmeter and current and allow temp. rise of 15°C *record reading on joulmeter Q and highest temp. reached Θ2 *use E=(mcΔΘ)w+(mcΔΘ)c |

Measure Specific Latent Heat of Fusion of Ice | *crush and dry ice (0°C)Θi-ice *get mass of calorimeter mc & water mw *heat water 5°C above room temp. Θi-water *add ice stir, temp. to 5°C below room temp.Θf *mass of all after *(mcΔΘ)i+(ml)i=(mcΔΘ)w+(mcΔΘ)c *find l |

Measure Specific Latent Heat of Vaporisation of Water | *mass of calorimeter mc & water mw *cool water 5°C below room temp. Θi *generate steam with steam trap *heat to 5°C above room temp. Θf *get new mass of all after *use (mcΔΘ)s+(ml)s=(mcΔΘ)w+(mcΔΘ)c *find l |

The Focal Length of a Concave Mirror *GRAPH | *non symmetrical letter (object) *get approx. focal length *make sure object distance>approx. focal length *get sharpest image on screen *get: distance u and v *repeat with range of u *formula: 1/f=1/u+1/v *find f |

To Verify Snell's Law and hence measure the refractive index of glass. *GRAPH | *two pins mark incident ray *method of no parallax 2 pins on opposite side (emergent ray) *mark: around block, rays in & out, normal. *join incident and emergent ray to get refracted ray *protractor: measure angle of i and r *find sini/sinr of range |

Refractive index of a liquid by measuring real and apparent depth | *fill beaker to top, pin at bottom *other pin in retord stand *line up image in mirror and pin in water *back of mirror to pin in retord stand = apparent depth *back mirror to bottom of beaker = real depth *refractive index=real/apparent |

Focal length of a convex lens *GRAPH | *same as concave mirror |

Measure the wavelength of Monochromatic light | *laser 90° to wall(metre stick) and diffraction grating *n=0 at 50cm mark *measure distance from n=0 to n=1, n=2 & n=3 *use trig TanΘ=o/a to find Θ for each n value *formula: nλ=dSinΘ to figure out λ(wavelength) *d=1/x÷1000 when x is in mm |

Investigate the variation of the fundamental frequency of a stretched string with length f∝1/l *GRAPH | *sonometer length as long as possible *tension constant value: when lowest frequency causes resonance *strike next highest tuning fork and adjust length until resonance occurs *get range of values: f, l & 1/l *all values of fxl should be approx same |

Investigate the variation of the fundamental frequency of a stretched string with tension f∝√T *GRAPH | *length about 1/3 of max length- keep constant *use lowest frequency tuning fork and adjust tension until resonance occurs *record range of values for tension and frequency |

To measure the Speed of Sound in air using a Resonance tube. *GRAPH | *using fork of highest frequency, adjust length until loudest sound occurs *record length l (top of water to top of tube) and frequency f *Repeat with different frequencies *Measure internal diameter of resonance tube fix to 0 error *c=4f(l+0.3d) |

Demonstrate Ohm's Law *GRAPH | *circuit with rheostat, power supply, coil of wire, voltmeter & ammeter *by varying rheostat, current and p.d are varied *measure a series of values for I and corresponding V *I∝V |

Verify Joule's Law: Change in temp. due to a current ∝ I^2 (ΔΘ∝I^2) *GRAPH | *circuit: power supply ammeter rheostat heating coil *known volume of water:calorimeter *current of 0.5A & start clock *note time passed *turn off, stir and note highest temp. reached *repeat with larger I values *all ΔΘ/I^2 values should be equal |

To measure resistivity of the material of a wire | *check micrometer for 0 error & note *measure diameter: a few points, correct & get average *ensure wire is straight & clamp to metre stick *switch on ohmmeter & connect probes *allow for resistance of leads *resistance between 2 points *ρ=Rπd^2/4l |

Investigate the variation of the resistance of a Metallic Conductor with temperature *GRAPH | *coil of wire to ohmmeter note resistance *boiling tube of glycerol, note temp (also temp. of coil) *measure approx. resistance of coil *measure resistance of leads (subtract) *fill beaker with cold water *for each 10°C rise record resistance &temp. |

Investigate the variation of Resistance of a thermistor with temperature *GRAPH | *thermistor to ohmmeter note resistance boiling tube of glycerol, note temp. (also temp. of thermistor) *measure approx. resistance of thermistor *heat *for every 10°C rise, record temp. and resistance |

Investigate variation of current (I) with p.d (V) :Metallic Conductor :Filament Bulb :Copper Electrodes :Semi-conductor | *D.C power supply *Ammeter *Rheostat *Voltmeter *Adjust rheostat and begin with small p.d *Measure and record p.d (v) and current (I) *Repeat and increase p.d. and record range of values **semi-conductor forward: milli-out, reverse: micro-in |