Physics 5054 · O Level · Circuit diagrams and circuit components

Circuit diagrams and circuit components — practice question

Fig. 9.1 shows a circuit diagram. The battery has an electromotive force (e.m.f.) of 12 V.
(a)[2]

Explain what the term electromotive force means.

(b(i)-1)[1]

State the relationship between the current $I_B$ in the battery, the current $I_1$ in the $18\,\Omega$ resistor and the current $I_2$ in the $30\,\Omega$ resistor.

(b(i)-2)[1]

State an equation connecting the e.m.f. $E$ of the battery with the potential difference $V_1$ across the $18\,\Omega$ resistor and the potential difference $V_2$ across the $30\,\Omega$ resistor.

(b(ii))[2]

Calculate the current in the battery.

(b(iii))[1]

Calculate the potential difference (p.d.) across the $18\,\Omega$ resistor.

(b(iv))[2]

Calculate the power produced in the $18\,\Omega$ resistor.

(c)[2]

State Ohm’s law and describe one restriction on this law.

(d(i))[1]

State the relationship between the resistance $R$ and the length $l$ of a wire when the cross-sectional area is constant.

(d(ii))[1]

State the relationship between the resistance $R$ and the cross-sectional area $A$ of a wire when the length is constant.

(e)[2]

State the colours of the bands on the $30\,\Omega$ resistor: first band, second band, third band.

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