The results of an experiment to determine the e.m.f. E and internal resistance r of a power supply are shown in Table. Plot a suitable graph and use it to find E and r.

V / V	1.43	1.33	1.18	1.10	0.98
I / A	0.10	0.30	0.60	0.75	1.00

 

A car battery has an e.m.f. of $12 \mathrm{V}$ and an internal resistance of $0.04\Omega$. The starter motor draws a current of $100 \mathrm{A}$.

Calculate the terminal p.d. of the battery when the starter motor is in operation.

A car battery has an e.m.f. of $12 \mathrm{V}$ and an internal resistance of $0.04\Omega$. The starter motor draws a current of $100 \mathrm{A}$.

(b) Each head lamp is rated as $\text{'}12\mathrm{V},36\mathrm{W}\text{'}$. Calculate the resistance of a headlamp.

A car battery has an e.m.f. of $12 \mathrm{V}$ and an internal resistance of $0.04\Omega$. The starter motor draws a current of $100 \mathrm{A}$.

(c) To what value will the power output of each headlamp decrease when the starter motor is in operation? (Assume that the resistance of the headlamp remains constant.)

Determine the range of $V_{\text{out }}$ for the circuit in Figure as the variable resistor $R_2$ is adjusted over its full range from $0\Omega$ to $40\Omega$. (Assume the supply of e.m.f. $10 \mathrm{V}$ has negligible internal resistance.)

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.