Generated by claude-sonnet-4-6 · 2026-06-15 06:42 · grounding rag
Model Answer
(a)
(i) Battery (cell) — A battery maintains a constant potential difference in a circuit.
(ii) Rheostat (variable resistance) — A rheostat is used to change (vary) the electric current in a circuit.
(b)
Given: V₁ = 110 V, I₁ = 5 A
Resistance of heater: $R = \dfrac{V_1}{I_1} = \dfrac{110}{5} = 22\ \Omega$
When V₂ = 220 V:
$$I_2 = \frac{V_2}{R} = \frac{220}{22} = \textbf{10 A}$$
The current flowing through the heater will be 10 A.
Source: Chapter 11 – Electricity, Section 11.3 (Circuit components) and Example 11.4 (Ohm's law application)
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Explanation
- For (a)(i), a battery is the standard answer; some students write "cell" which is also acceptable.
- For (a)(ii), the answer expected is rheostat (variable resistance) — it is listed in Table 11.1 of the textbook.
- For (b), the key step is first finding resistance using Ohm's law (R = V/I), then applying it again at the new voltage. The resistance of the heater stays constant (metallic conductor). This mirrors Example 11.4 exactly.
- Always show formula, substitution, and unit — examiners award step marks.