The circuit diagram shows a resistor and a thermistor connected in series with a 6 V battery - Leaving Cert Physics - Question d - 2014

The resistances are in series, so the total resistance (R_total) is the sum of the individual resistances:

$R_{total} = R_1 + R_2 = 50 \Omega + 450 \Omega = 500 \Omega$

Using Ohm's law, the current (I) in the circuit can be calculated as follows:

$I = \frac{V}{R_{total}} = \frac{6 \text{ V}}{500 \Omega} = 0.012 \text{ A} = 12 \text{ mA}$

The potential difference (V) across the 50 Ω resistor can be calculated using Ohm's law:

$V = I \times R = 0.012 \text{ A} \times 50 \Omega = 0.6 \text{ V}$

If the temperature increases, the resistance of the thermistor tends to decrease. Thus, the overall resistance of the circuit would change, typically decreasing.