Paper 1 required practicals

Question 1

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

Answer 1

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 2

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

Answer 2

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 3

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

Answer 3

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 4

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

Answer 4

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 5

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

Answer 5

Independent - length of wire - continuous

Dependent - current and voltage to calculate resistance -continuous

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

Question 6

Resistance PAG 1 - Describe the expected results

Answer 6

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 7

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

Answer 7

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 8

Resistance PAG 1 - Describe a suitable risk assessment

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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 13

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

Answer 13

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

Question 14

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

Answer 14

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 15

I-V graphs PAG - Define ohms law

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

No the graph curves and levels off so isnt directly proportional

Question 18

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

Answer 18

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 19

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

Answer 19

No current in the negative direction.

In the positive direction current increases quickly

Question 20

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

Answer 20

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

Question 21

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

Answer 21

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 22

SHC PAG - State the units of SHC

Answer 22

J/kg^oC

Question 23

SHC PAG - Define SHC

Answer 23

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

Question 24

SHC PAG - What measurements are needed?

Answer 24

c = Energy / (mass x temperature change)

so need to measure:

Energy provided

mass

temperature change

Question 25

SHC PAG - How can the energy provided be found?

Answer 25

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 26

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

Answer 26

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

Question 27

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

Answer 27

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)