Physics 9702 · AS & A Level · Electric potential

Electric potential — practice question

Suggest one electrical sensing device for each case that may be used to monitor changes in
(a(i))[1]

the light intensity.

(a(ii))[1]

the crack width in a welded joint.

(a(iii))[1]

the ultrasound beam intensity.

(b)

A student sets up the circuit in Fig. 9.1 to detect temperature changes over the range $0\,^{\circ}\text{C}$ to $100\,^{\circ}\text{C}$. The thermistor has resistance $R_{T}$ and the resistor has resistance $R$. The student measures the potential difference $V_{\text{OUT}}$. State and explain

(b(i))[3]

whether $V_{\text{OUT}}$ rises or falls as the thermistor temperature rises.

(b(ii))[2]

whether the change in $V_{\text{OUT}}$ varies linearly with the thermistor’s temperature change.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: a light-dependent resistor (LDR)

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