Questions to probe understanding: cells and currents

What the Activity is for

The diagnostic questions can be used to check the pupils' understanding of key ideas introduced in this episode.

What to Prepare

• printed copies of the questions

Support sheet

What Happens During this Activity

The questions might be used for homework or as the basis for discussion in class.

The question Which way around? targets the point that the direction that individual cells are connected in influences their effect on the circuit. Both cells need to be pointing in the same direction to provide a greater push on the charged particles, and to shift more energy to the charged particles as they pass through the battery.

• Circuit (b) is the brightest; the batteries are pointing in the same direction.
• Circuit (c) is the dimmest; the bulb will not light at all.
• Circuits (a) and (d) are of the same brightness; in circuit (d) two of the batteries are connected in the same direction, whilst the third is facing in the opposite direction.

The question Remove battery probes the way in which the current changes when the number of batteries in a circuit is reduced. When one of the batteries is removed, the current in the bulb gets less (but is not zero) because one battery exerts a smaller push on the charged particles.

The question Add battery probes the way in which the bulb brightness changes when the number of batteries in a circuit is increased. When an extra battery is added the bulb gets brighter because the extra battery pushes a bigger current around the circuit, and with the extra battery more energy is shifted by the charged particles.