Physics required practicals

Specific Heat Capacity Method

• Measure the mass of the solid metal block using a balance

• Wrap a layer of insulating material around the block eg bubble wrap

• Put a thermometer in the block ( adding a few drops of oil before )

• Place an immersion heater in the bigger hole

• Attach this to a voltmeter in parallel and an ammeter in series, along with a power pack but don't turn it on yet

• Record the initial temperature with the thermometer

• Then turn on the heater with the power pack

• Every 1 minute for up to 10 minutes record the temperature, the current and the potential difference

• Then after 10 minutes turn the power pack off a wait for the block to reach its highest temperature

• Then using P = IV and P=E/t work out the energy transferred and plot this against temperature

• Work out specific heat capacity by finding the reciprocal of gradient of the line

Sources of Error

Experimental error

• Some of the heat lost from the block to the surroundings could make value higher than expected

Sources of Hazard

• Could burn your skin touching the hot immersion heater

Spring Extension Practical Method

• Attach a clamp stand securely to a table using a G clamp
• Use bosses to attach two clamps to the stand
• Adjust the ruler so it is vertical and make sure it's zero level to the top of the spring
• Measure and record the unloaded length of the spring
• Hang a 1N force on the end of the spring, and measure the new length of the spring
• Record the results down and calculate the spring extension
• Repeat the last 2 steps adding 1N force each time up to 10N
• Plot a graph of spring extension against force

Sources of Error

• Parallax error
• Not clamping the ruler vertically

Safety Precautions

• Wear safety goggles to avoid the spring accidentally entering the eye
• Stand away so that the weights don't accidentally drop onto your foot

Resistance and Wire Length Method

• Set up a circuit with a voltmeter in parallel to the ruler and wire being tested ( the voltmeter tells you the potential difference) and an ammeter in series in the circuit ( the ammeter tells you the current )
• Attach the metre ruler with wire. Use crocodile clips to attach the wire to the circuit
• Place the crocodile clips 100cm apart
• Turn on the power pack and measure the pd and current and record the results down
• Turn the power pack off and reduce the wire length between the clips by 10cm and then repeat these steps for all wire lengths down to 10cm
• Calculate the resistance for each wire length using V=IR
• Record the resistance against wire length in a graph

Sources of Error

Experimental Error

• The temperature of the wire may have increased, increasing resistance the longer the circuit was on for

Safety Precautions

• Turn the power off between readings to make sure the wire doesn't overheat and ignite
• Be careful touching the wire not to burn yourself

Density Practical Method
Regular objects

• Measure the base, height and length of the object and use volume = length x base x height to work out volume
• Measure the mass of the object using a balance
• Using density = mass / volume work out the density of the object

Density Practical Method
Irregular objects

• Fill a eureka can up to just below the spout with water
• Place a measuring cylinder just below the spout
• Place the object in the water and the volume of water displaced and collected in the measuring cylinder is the volume of the object
• Using a balance find the mass of the object
• Using density = mass / volume find the density of the object

Sources of Error

• Zero error on the balance
• Read the reading for volume of water displaced incorrectly

Safety Precautions

• Avoid spilling water onto the balance ( so keep it away from eureka can ) to avoid any issues with electrocution due to water mixing with electricity

Insulation Method

• Use the kettle to boil water and then put 80 ml of this hot water into a 100 ml beaker.
• Place the small 100 ml beaker inside the large beaker.
• Use a piece of cardboard, with a hole for the thermometer, as a lid for the large beaker.
• Insert the thermometer through the hole in the cardboard lid so that its bulb is in the hot water.
• Record the temperature of the water and start the stopwatch. Record the temperature of the water every 5 minutes for 20 minutes.
• Repeat the previous steps but this time fill the space between the small and the large beaker with an insulating material. Make sure that you use the same volume of water each time.
• Draw cooling curve graphs by plotting temperature against time for each insulator.
• From your graphs, determine which material is the best insulator.

Sources of Error

Systematic errors

• Make sure the water is the same temperature for all materials
  Random Errors
• Read thermometer at eye level to avoid parallax error
• Make sure the hole for the thermometer isn't too big so heat doesn't escape through it

Safety Precautions

• Be careful when handling boiling water not to burn yourself
• Wear safety goggles to avoid any hot water entering your eye