Question 1

Paper 2Hard10 marks

Two samples, XX and YY have the same length and cross-sectional area. Sample XX is a metal; sample YY is an unknown material. Each sample is connected separately to a variable d.c. supply. The potential difference VV across the sample and the current II through it are measured at the same temperature.

Sample XSample YI = 20.0VI = 0.0500V0102030405060708090100110012345.00.000.050.100.150.200.250.30012345.0Current, I / mACurrent, I / µAPotential difference, V / VPotential difference, V / V
(a)

Using Figure 1, read the current in each sample when the potential difference is 3.0 V3.0\ \text{V}

[2]
(b)

Use the reading for sample XX at 3.0 V3.0\ \text{V} to determine its resistance.

[2]
(c)

A third test uses a sample SS which is either XX or YY It is connected in series with a 50 Ω50\ \Omega resistor to a 6.0 V6.0\ \text{V} supply. The current in the circuit is 60 mA60\ \text{mA} Use the circuit information and Figure 1 to determine whether SS matches XX or (Y). Show your reasoning.

[4]
(d)

A student claims that sample YY has no mobile charge carriers because its current is almost zero. Assess this claim using Figure 1 and the idea of mobility of charge carriers.

[2]

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