O-LevelPhysicsElectricity5054/21 · May/June 2019 · Q55 Marks

A student uses the circuit shown in Fig. 5.1 to investigate a resistor R. [Figure 5.1]

(a)Describe how the student uses the apparatus in Fig. 5.1 to obtain a range of ammeter and voltmeter readings.[1]
(b)(i)The readings obtained are shown in Table 5.1. [Table 5.1] State Ohm's law.[2]
(b)(ii)Using the results in Table 5.1, show that the resistor obeys Ohm's law.[1]
(b)(iii)The student has available an ammeter with five ranges marked: • 0–10 A • 0–200 mA • 0–20 mA • 0–2 mA • 0–0.2 mA Suggest how the student makes best use of the different ranges during the investigation.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[1] adjusts the variable resistor / rheostat or change the number of cells
[1] current proportional to voltage or V = kI where k is a constant
[1] provided temperature / physical conditions unchanged
[1] at least two values of V/I or I/V shown to be the same;
[1] use 0-10 A range for 220 and 320 mA readings and 0-200 mA range for 100 mA reading or start with 10 A/highest range and either reduce to 200 mA for last reading reduce range and keeping high value on scale / not over scale

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