ATP Papers Flashcards
Safety Precautions
Live wires should not be touched.
Hot objects should not be touched with bare hands - gloves should be used
Circuit connections should be checked and approved by the teacher and then only the circuit should be switched on
While changing components of the circuit the power should be switched off so that one should not experience electric shocks.
Safety goggles, gloves and other safety components should be used while handling experiments.
While handling a mercury thermometer one should take care of the mercury spills.
Find Specific Heat Capacity of a Substance
Apparatus: Solid block, Drill, Thermometer, Heater (of known power), Cotton wool.
Procedure:
Drill two holes in the block.
Measure the mass of the block.
Place the heater in one of the blocks, the thermometer in the other.
Use cotton wool to properly insulate/lag the block.
Note the initial temperature of block and turn on heater for
x seconds
Calculate Heat Energy Supplied by heater using formula Q=Pt.
Note the final temperature of block.
Specific heat capacity =
Q/m×Δt
Find the cooling rate of a liquid
Apparatus: Heater, Thermometer, Beaker, Stopwatch, Beaker containing Water.
Procedure:
Place heater into beaker and turn it on to raise the temperature of water to 60°C
Stir the contents of the water and place thermometer into the beaker.
Note the starting temperature and turn on the stopwatch.
Take readings of the thermometer and stopwatch at regular intervals (e.g. 60 sec).
Draw up a table and plot a graph to conclude your experiment.
Find the better insulator
Apparatus: Two large cans, two small cans, cotton wool, polystyrene beads, boiling water, thermometers, stopwatch
Procedure:
Put the small cans into the large cans and insulate the small can with (i) cotton wool and (ii) polystyrene beads
Pour boiling water into the small cans and place the thermometers in them.
Start the stopwatch and take readings of temperature at regular intervals.
Record readings in a table for each insulator.
The small can that has the higher temperature over the fixed period is better insulated.
Hence, object that provides a less temperature loss over the period is the better insulator.
Refraction of Light
Apparatus: Ray Box, Rectangular piece of glass, Plain paper, Pencil.
Procedure:
Place the Plain paper below the rectangular piece of glass.
Project a ray towards the glass.
Make two points to mark the incident ray, two to mark the refracted ray and two to mark the emergent ray.
Join all the lines, measure the angles and calculate refractive index.
Repeat with different angles; Snell’s law shown.
Find the relation between resistance and temperature
Apparatus: Resistor, Battery, Connecting wires, Ammeter, Voltmeter, Oven.
Procedure:
Make a circuit with the battery, connecting wires, ammeter and voltmeter, resistor.
Measure the resistance of the resistor using the formula R=V/I.
Heat the resistor in the oven. Place the resistor back into the circuit.
Measure the readings again and calculate R=V/I.
Draw up a conclusion about how the resistance increases as temperature increases.
Find the speed of sound
Apparatus: Two observers, Gun, Stopwatch.
Procedure:
Two observers are set apart at a known distance.
One observer has the gun, the other has the stopwatch.
Observer A fires the gun, Observer B starts the stopwatch when he sees the puff of smoke.
Observer B stops the stopwatch when he hears the sound and the time is noted.
Apply Speed=distance/time
The observers swap positions and repeat the experiment.
The values are averaged and the speed of sound is obtained.
Find the centre of mass
Centre of mass of a plane lamina:
Make a hole in the lamina.
Hang it so it can swing freely.
Hang a plumb line in the hole and mark the line it passes through.
Repeat the procedure again to get another line
Their intersection point is the center of mass.
Stability of simple objects:
The position of the center of mass affects an object’s stability. If the center of mass of an object is low, it is less likely to tip if tilted.
To increase stability: (i) Increase surface area (ii) widen the base of the object.
