Physics 9702 · AS & A Level · Kirchhoff's laws

Kirchhoff's laws — practice question

(a(i))[1]

For a cell, explain what the term electromotive force (e.m.f.) means.

(a(ii))[1]

For a cell, explain what the term internal resistance means.

(b(i))[2]

Figure 5.1 shows batteries A and B, with resistor $R$, connected in series. Battery A has an e.m.f. of $3.0\,\text{V}$ and an internal resistance of $0.10\,\Omega$. Battery B has an e.m.f. of $12\,\text{V}$ and an internal resistance of $0.20\,\Omega$. Resistor $R$ has a resistance of $3.3\,\Omega$. Use Kirchhoff’s second law to calculate the current in the circuit.

(b(ii))[2]

Calculate the power transformed by battery B.

(b(iii))[2]

Calculate the total energy lost each second in resistor $R$ and the internal resistances.

(c)[1]

The circuit of Fig. 5.1 may be used to store energy in battery A. Suggest how your answers in (b) provide support for this statement.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Energy transferred from chemical to electrical when current flows / circuit complete

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI