General Important Practical Stuff

Question 1

How do we justify the number of significant figures used in a practical?

Answer 1

Should use the resolution of the measuring equipment

Question 2

How do we estimate the difference in … using a graph?

Answer 2

Count squares

Question 3

How do we justify if the results of an experiment are consistent with an equation?

Answer 3

Analyse the graph
e.g:
-straight line
-intercept is consistent
-passes through all error bars
-values used linked to values in equation
(e.g - using l for V in PV=nRT and V is proportional to T so straight line)

Question 4

How would we get A=Aoe-kt in graphical form?

Answer 4

Take logs

Question 5

How do we determine a value form a graph?

Answer 5

Gradient

Question 6

how do we “justify” a claim?

Answer 6

Do calculations

Question 7

% difference between 2 values

Answer 7

Calculates-actual/actual x100

Question 8

What do we need to do when going from an equation to a graph?

Answer 8

Input the equation into the equation of a straight line
y = mx + c

Question 9

How do we know which values to put where in the equation of a straight line?

Answer 9

Think…
What are the constants?
What are the variables (these will be x and y)

Question 10

How do we go from having a graph to an equation?

Answer 10

• locate 2 well separated x and y points
• calculate the gradient
  -can calculate c using y=mx + c

Question 11

How can we work out the accuracy of a value?

Answer 11

Work out the uncertainty
Does the value fit into the uncertainty value?