What is the voltage across the $3.0\mathrm{k}\Omega$ resistor in Figure when the light intensity is 10 lux?

The circuit shown in Figure produces a decreasing output voltage when the light intensity increases. How can the circuit be altered to produce an increasing output voltage as the light intensity increases?

An LDR used as a sensor.

Design a circuit using the thermistor in Figure that uses a cell of $10 \mathrm{V}$ and produces an output voltage of $5 \mathrm{V}$ at $50°\mathrm{C}$. Explain whether the voltage output of your circuit increases or decreases as the temperature rises.

Variation of resistance with temperature.

To make a potentiometer, a driver cell of e.m.f. $4.0 \mathrm{V}$ is connected across a $1.00 \mathrm{m}$ length of resistance wire.

(a) What is the potential difference across each $1 \mathrm{cm}$ length of the wire? What length of wire has a p.d. of $1.0 \mathrm{V}$ across it?

To make a potentiometer, a driver cell of e.m.f. $4.0 \mathrm{V}$ is connected across a $1.00 \mathrm{m}$ length of resistance wire.

(b) A cell of unknown e.m.f. $\mathrm{E}$ is connected to the potentiometer and the balance point is found at a distance of $37.0 \mathrm{cm}$ from the end of the wire to which the galvanometer is connected. Estimate the value of $\mathrm{E}$. Explain why this can only be an estimate.

To make a potentiometer, a driver cell of e.m.f. $4.0 \mathrm{V}$ is connected across a $1.00 \mathrm{m}$ length of resistance wire.

(c) A standard cell of e.m.f. $1.230 \mathrm{V}$ gives a balance length of $31.2 \mathrm{cm}.$ Use this value to obtain a more accurate value for $\mathrm{E}$.

A resistor of resistance $6.0\Omega$ and a second resistor of resistance $3.0\Omega$ are connected in parallel across a battery of e.m.f. $4.5 \mathrm{V}$ and internal resistance $0.50\Omega$. What is the current in the battery?

(A) $0.47 \mathrm{A}$

(B) $1.8 \mathrm{A}$

(C) $3.0 \mathrm{A}$

(D) $11 \mathrm{A}$