required practicals

Density

1. Measure mass of objects on balance

2. Place measuring cylinder under the spout of eureka can

3. Lower object into water, measure volume displaced using measuring cylinder

4. Find density using density = mass / volume

Liquid density- beaker on balance- 0 the mass

Pour in liquid- new mass = mass of liquid

Volume measure using equation

Errors- water splashes or not filly spout- lower volume, zen error on balance, parallax reader

Length and resistance

1. Safety- don’t touch bare wire- hot

2. Place crocodile clips and wire in line with ruler- connect to 20cm apart, measure current and PD, find resistance

3. Increase length by 10cm, record new readings

4. Disconnect between readings to stop wire hot

5. Resistance and length are directly proportional

6. More collisions between electrons

Current / pd characteristics

Variable resistor- changes resistance

Fixed resistor, filament bulb, diode or LED

Measure current using ammeter and PD

Use variable resistor to change resistance- range of values

Record new values of current and pd

Reverse the connections on the cell to obtain negative values

Plot graph- positive and negative- fixed resistor is directly proportional (ohms law)

Filament- resistance increases as temp increases so current stops- more collisions between electrons- resistance goes up

Diode- only flows in one direction

Disconnect between readings- stop wires getting hot

Electrical safety- don’t use broken wires or water near

Specific heat capacity

1. Measure mass of metal block using balance

2. Metal block with immersion heater, joule-meter and thermometer. Measure initial temperature using thermometer

3. Turn heater on and place in metal block, start stopwatch

4. Record temperature every 2 mins and record energy change on the joule-meter OR use ammeter and voltmeter to measure power and then energy

5. Use equation for measure SHC

6. Not proportional- time taken for heater to heat up

7. Gradient of line = change in temp/ change in time

8. Safety- don’t touch heater

9. Errors- energy lost to surroundings, use insulation around block and lid