Checking an initial understanding: voltage

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 these three questions

Support sheet

What Happens During this Activity

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

Four batteries: designed to probe pupils' understanding of battery voltage.

• Battery d
• It has the largest voltage, so it pushes the biggest current round.

Battery voltage: probes understanding of the relationship between the battery voltage and the voltage across the external circuit.

• V₁ is 3 volt
• This must be the reading on the voltmeter because the voltage across the battery equals the voltage across the single resistor. The energy per coulomb supplied to the circuit at the battery equals the energy per coulomb shifted to the surroundings at the resistor.

Batteries: probes pupils' understanding of current and voltage.

• You cannot buy a 1.5 ampere battery because batteries are specified in terms of voltage. The current in a circuit depends on both the battery voltage and the circuit resistance. It does not make sense to talk of a 1.5 ampere battery. The battery can supply a full range of currents.