Six mark questions

Six mark questions are often the questions that people find the most difficult. In all longer answer questions, but especially the six mark ones, it is important that you plan your answer and not just rush into it. After all, you would plan an essay or short story before starting. Without a plan it is easy to stray away from the key point and lose marks, get steps in a process in the wrong order or forget key bits of information.

Six mark questions will start with command words such as 'describe' or 'explain'. The command words 'describe' and 'explain' can be confusing. If you are asked to describe a graph, you will be expected to write about its overall shape, whether it is linear or curved, the slope of gradients etc. If you are asked to explain why a pattern or trend is seen in a graph, you will be expected to use your science knowledge, not just say what you see (which is a description), eg 'The graph shows the number of radioactive nuclei decreases as time increases. It does this because…'.

'Explain how' and 'why' questions often have the word 'because' in their answer. 'Describe' questions don't.

The number of marks per question part is given in the form '[6 marks]'. It is essential that you give as many different points in your answer as possible, linking these together. Often, you will be asked to compare two things, make sure that you include both in your answer otherwise, you are likely to limit your score to two marks out of six marks.

Edexcel questions courtesy of Pearson Education Ltd.

Sample question 1 - Foundation and Higher

Question

The first public power station was built in the centre of New York. It used generators to supply direct current at 110 V. The cables had to go underground and they could only supply nearby shops and offices. The electricity was mainly used for electric light. The development of alternating current generators led to major changes in the way electricity is transmitted and used.

Compare the modern National Grid system with the early system in New York. [6 marks]

The modern National Grid consists of transformers which improve the efficiency by reducing heat loss in the transmission wires [1]. Near the power station, a step-up transformer is used to create a high voltage [1] and near homes, a step-down transformer is used to reduce the voltage to a safe level for use [1]. The early New York system did not use transformers so could only supply nearby shops and offices as there would be too much energy loss in long transmission wires [1]. Most of the National Grid uses overhead wires which are easy to maintain [1]. The early New York system used underground wires which are harder to maintain [1].

Answering tip

Briefly plan the key points you want to include in your answer. For example:

  • explain the setup of the current National Grid
  • compare this to the setup of the early New York system
  • comment on any other points suggested in the question

Sample question 2 - Higher

Question

The diagram shows a model used to generate electricity from water waves in a tank. A ball floats on the surface of the water in the tank. A coil of wire is fixed to the floor of the tank. A magnet is suspended from the ball inside the coil.

When a wave is sent along the surface of the water the ball moves up and down.

A ball floats on the surface of the water in the tank. A coil of wire is fixed to the floor of the tank. A magnet is suspended from the ball inside the coil.

The graph shows the current induced in the coil.

A graph with two long curves. The first peaks above the line at 0.30 and the second peaks below the line at -0.30

Explain how this current is induced in the coil in the model.

You should refer to the model and to the labelled points on the graph in your answer. [6 marks]

The magnet moving in the coil induces a current [1]. When the magnet changes direction [1], the current changes direction [1]. At P and R the magnet is moving in opposite directions [1]. When the magnet is moving faster [1] a greater potential difference is induced [1].

Answering tip

Briefly plan the key points you want to include in your answer. For example:

  • consider the relative motion that induces the current
  • why does the current in the graph change direction?
  • link this to points P and R from the graph

Sample question 3 - Foundation and Higher

Question

The diagram shows how electricity produced at a power station is transmitted to distant houses.

Main features of the national grid from power station to step-up  transformers then transmission lines, step-down transformers and finally consumers

The step-up transformers and step-down transformers are not 100% efficient.

By using transformers, energy losses in the transmission lines are reduced.

Explain how this reduction is achieved, even though some energy is wasted in the transformers themselves. [6 marks]

An explanation linking some of the following points:

Basic ideas:

  • transmission lines have resistance
  • the current warms the transmission wires
  • energy is wasted as heat
  • transformers change voltage and/or current
  • step-up transformers increase the voltage/RA for step-down transformers
  • step-up transformers decrease the current/RA for step-down transformers

Linked ideas:

  • the long transmission lines have high resistance
  • power depends on both current and voltage
  • power = current × voltage (P = I × V)
  • at high voltage, the same power needs less current
  • correct mention of turns ratio related to voltage change
  • a smaller current in a wire produces less heat
  • high voltage transmission saves more energy than is lost in the transformers

[6]