Paper 1 required practicals

Question 1

Insulation PAG - If you want to investigate the effectiveness of different materials as insulators state the variables and whether they are continuous, discrete or cateroric

Answer 1

Independent - type of material - catergoric

Dependent - temperature loss - continuous

Controls - Volume(continuous), starting temperature(continuous), thickness of insulating material (continuous)

Question 2

Insulation PAG - If you want to investigate the effectiveness of different materials as insulators state what type of graph you would draw and why?

Answer 2

Bar chart - one of the variables is catergoric

Question 3

Insulation PAG - If you want to investigate the effectiveness of different materials as insulators describe a suitable method

Answer 3

1. Boil a kettle and measure a set volume of boiling water in a measuring cylinder.
2. Pour this boiling water into a beaker and wrap with a particular type of insulator
3. Use a thermometer to measure the initial temperature
4. Use a stop clock to time for 10 minutes and then measure the final temperature.
5. Calculate the temperature change (Initial temp - final temp)
6. Repeat to calculate an average
7. Repeat for all the different insulators making sure the starting temperature and volume are controlled.

Question 4

Insulation PAG - If you want to investigate the effectiveness of different materials as insulators describe what would cause errors in the experiment and how they would be reduced.

Answer 4

Heat lost to the surrounding, place a lid on top of the beaker.

Question 5

Insulation PAG - If you want to investigate how the thickness of an insulator affects the rate of heat loss state the variables and whether they are continuous, discrete and catergoric

Answer 5

Independent - Number of layers of insulation - discrete

Dependent - temperature loss - continuous

Controls - Volume(continuous), starting temperature (continuous), type of insulation (categoric)

Question 6

Density PAG - how can the density of a regular shape be found?

Answer 6

Measure the mass using an electronic balance

Measure the length of each side using a ruler

Calculate volume (length x breadth x width)

Calculate Density (mass / volume)

Question 7

Density PAG - how can the density of a irregular shape be found?

Answer 7

Measure the mass using an electronic balance

Measure the volume with a eureka can by collecting the displaced water and using a measuring cylinder

Calculate Density (mass / volume)

Question 8

Density PAG - how can the density of a liquid be found?

Answer 8

Measure the volume with a measuring cylinder

Place a beaker on an electronic balance and record the mass.

Add the liquid to the beaker and record the new mass

Calculate the mass of the liquid (final mass - initial mass)

Calculate Density (mass / volume)

Question 9

Resistance PAG 1 - Describe a method to find the resistance of a wire

Answer 9

Set up a power pack connected to an ammeter in series and to a resistance wire and a voltmeter in parallel to the wire.

Set the crocodile clips so they are 10 cm apart.

Measure the current with an ammeter and the potential difference with a voltmeter.

Calculate the resistance using R = V/I

Repeat for other lengths

Question 10

Resistance PAG 1 - State the variables and whether they are continuous, discrete and catergoric

Answer 10

Independent - length of wire - continuous

Dependent - current and voltage to calculate resistance -continuous

Controls - Temperature of wire - continuous, type of wire catergoric

Question 11

Resistance PAG 1 - Describe the expected results

Answer 11

As length of wire increases so does the resistance. Length and resistance will be directly proportional to each other. The graph would be a straight line through the origin.

Question 12

Resistance PAG 1 - what would have caused the main error in the experiment and how could it be reduced.

Answer 12

Wire heating up - use a small current and turn the power off after each reading so the wire cools down.

Measuring the length of the wire due to the thickness of the crocodile clips - use thiner crocodile clips.

Question 13

Resistance PAG 1 - Describe a suitable risk assessment

Answer 13

Wire will get hot - this could burn you - use a small current and turn the power off in-between readings

Question 14

Resistance PAG 2 - What happens to total resistance when resistors are added in series?

Answer 14

Total resistance will increase as the current (electrons) will need to pass through all resistors in series

Question 15

Resistance PAG 2 - What happens to total resistance when resistors are added in parallel?

Answer 15

Total resistance will decrease as the current (electrons) have more paths to take back to the battery.

Question 16

I-V graphs PAG - Describe the circuit needed to find the I-V characteristics of a component.

Answer 16

A power pack in series to an ammeter, a variable resistor and the component in question. A voltmeter in parallel to the component.

Question 17

I-V graphs PAG - Describe a method find the I-V characteristics of a component.

Answer 17

Set up the circuit and use the ammeter to measure the current and a voltmeter to measure the voltage.

change the resistance in the circuit using the variable resistor and measure the current and voltage again.

Repeat 6 times to collect enough data to draw a graph.

Question 18

I-V graphs PAG - Describe the graph for a resistor

Answer 18

A straight line through the origin - current and voltage are directly proportional and it obeys ohms law

Question 19

I-V graphs PAG - Explain the graph for a resistor

Answer 19

As potential difference increases there is a bigger push on the electrons so they move around the circuit more quickly. The flow of electrons is the current so current increases proportionally.

Question 20

I-V graphs PAG - Define ohms law

Answer 20

Current is directly proportional to potential difference as long as temperature remains constant

Question 21

I-V graphs PAG - Describe the graph for a bulb

Answer 21

As voltage increases so does the current but the current levels off and the graphs curves.

Question 22

I-V graphs PAG - Does a bulb obey ohms law?

Answer 22

No the graph curves and levels off so isnt directly proportional

Question 23

I-V graphs PAG - Explain the graph for a bulb

Answer 23

The bulb heats up which causes the atoms to vibrate faster and take up more space. This makes is harder for the electrons to travel down the wire. This causes the resistance to increase.

Question 24

I-V graphs PAG - Describe the graph for a diode

Answer 24

No current in the negative direction.

In the positive direction current increases quickly

Question 25

I-V graphs PAG - Does a diode obey ohms law?

Answer 25

No the graph isn’t a straight line through the origin.

Question 26

I-V graphs PAG - Explain the graph for a diode

Answer 26

In the negative direction a diode has a massive resistance which stops any current from flowing.

In the positive direction a diode has a low resistance so a large current can flow.

Question 27

SHC PAG - State the units of SHC

Answer 27

J/kg^oC

Question 28

SHC PAG - Define SHC

Answer 28

The amount of energy neeed to change the temperature of a 1 kg substance by one degree Celsius

Question 29

SHC PAG - What measurements are needed?

Answer 29

c = Energy / (mass x temperature change)

so need to measure:

Energy provided

mass

temperature change

Question 30

SHC PAG - How can the energy provided be found?

Answer 30

Method 1 - Use a joulemeter to measure the energy provided directly

Mathod 2 - Use an ammeter to measure current, voltmeter to measure voltage and stopwatch to measure time

Power = VI

Energy = power x time

Question 31

SHC PAG - What are the main causes of energy and how can they be reduced?

Answer 31

Heat losses to the surroundings, reduced by insualting the material that is being heated.

Question 32

SHC PAG - Describe a method to find the SHC of a material

Answer 32

Measure the mass of the material

Measure the initial temperature of the material

Place an electrical heater in the material.

Time for 10 minutes and then find the final temperature

Calcualate the temperature increase

Calcaute the SHC = Energy / (mass x temperature change)