describe specific heat Capacity
The specific heat capacity of a substance is the amount of energy required to raise the temperature of 1kg of a substance by 1 degree
specific heat capacity practical
- Place beaker on balance and press zero
- Add liquid (e.g oil) to beaker and record mass of liquid from balence
- Place a thermoneter and immersion heater into the oil
-Read starting temperature of the oil
-Wrap beaker in insulating foam to reduce thermal energy transfer to surroundings - connect a joulemeter and powerpack to immersion heater (joulemeter tells us how many joules of electrical energy pass into immersion heater)
- Leave set up for 30 minutes (allows temp to rise accurately enough so we can read on thermometer)
-read final temperature of liquid (oil)
-Calculate SHC with equation
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Sources of inaccuracy in the Specific heat capacity and how to fix
- Thermal energy passing out of the beaker into the air
-Solve this by using a insulator with a lower thermal conductivity
-Not all thermal energy passing through the oil.
-Ensure emersion heater is fully submerged
Incorrect reading on thermometer
- Use electronic temperature probe
Describe how to investigate the effectiveness thermal insulators
Place small beaker inside a larger beaker
- Boil water with kettle
-Transfer 80cm^3 of hot water into the small beaker
- use a piece of Carboard as a lid for the large beaker
- lid must have a hole for the thermometer
- we place thermometer through hole in the carboard lid
- bulb of thermometer must be in hot water
-we record starting temperatures of the water and start a stopwatch
- Record temperature of the water every three minutes for fifteen minutes
- Repeat experiment using same volume of hot water
- However, this time we use an insulating material (eg) bubble wrap to fill the gaps between the two beakers.
- Test range of different insulating materials. For example, cotton wool and polystyrene balls.
- Use same mass of insulating materials in each case
variables for Thermal insulators practical
independent variable - Type of insulating material
dependant - one that is measured for change each change in the independent variable e.g temp
Control - variables we do not allow to change. volume of water, mass of insulating and starting water temp.
Reflection and Refraction practical
- place a glass block on a piece of paper
- draw around the glass block
- use the ray box to shine a ray of light through the glass
block - mark the ray of light entering the glass block
- mark the ray of light emerging from the glass block
- join the points to show the path of the complete ray through
the block - and draw a normal line at 90 degrees to the surface
- use a protractor to measure the angle of incidence
- use a protractor to measure the angle of refraction
- use a ray box to shine a ray of light at a range of different
angles (of incidence) - increase the angle of incidence in 10 degree intervals
- from an angle of incidence of 10 degrees to an angle of
incidence of 80 degrees
