Define the ohm.

1. (a)Define the ohm.[1]
2. (b)A cell X of electromotive force (e.m.f.) 1.5V and negligible internal resistance is connected in series to three resistors A, B and C, as shown in Fig. 6.1. [Figure 6.1] Resistors A and B have resistances 6.0 Ω and 3.0 Ω respectively and are connected in parallel. Resistor C has resistance 4.0 Ω and is connected in series with the parallel combination. Calculate
3. (b)(i)the current in the circuit,[3]
4. (b)(ii)the current in resistor B,[1]
5. (b)(iii)the ratio power dissipated in resistor B power dissipated in resistor C[2]
6. (c)The resistors A, B and C in (b) are wires of the same material and have the same length.
7. (c)(i)Explain how the resistors may be made with different resistance values.[1]
8. (c)(ii)Calculate the ratio average drift speed of the charge carriers in resistor B average drift speed of the charge carriers in resistor C[2]
9. (d)A cell of e.m.f. 1.5V and negligible internal resistance is connected in parallel with cell X in Fig. 6.1 with their positive terminals together. State the change, if any, to the current in
10. (d)(i)cell X,[1]
11. (d)(ii)resistor C.[1]

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