A calculator is powered by a $3.0 \mathrm{V}$ battery. The calculator's resistance is $20\mathrm{k}\Omega$. Calculate the power transferred to the calculator.

An energy-efficient light bulb is labelled $\text{'}230 \mathrm{V},15 \mathrm{W}\text{'}$. This means that when connected to the $230 \mathrm{V}$ mains supply it is fully lit and changes electrical energy to heat and light at the rate of $15 \mathrm{W}$. Calculate the current in the bulb when fully lit.

An energy-efficient light bulb is labelled $\text{'}230 \mathrm{V},15 \mathrm{W}\text{'}$. This means that when connected to the $230 \mathrm{V}$ mains supply it is fully lit and changes electrical energy to heat and light at the rate of $15 \mathrm{W}$. Calculate:

(b) Its resistance when fully lit.

A $12 \mathrm{V}$ car battery can supply a current of $10 \mathrm{A}$ for $5.0$ hours. Calculate how many joules of energy the battery transfers in this time.

A lamp is operated for $20 \mathrm{s}$. The current in the lamp is $10 \mathrm{A}$. In this time, it transfers $400 \mathrm{J}$ of energy to the lamp. Calculate:

(a) How much charge flows through the lamp.

A lamp is operated for $20 \mathrm{s}$. The current in the lamp is $10 \mathrm{A}$. In this time, it transfers $400 \mathrm{J}$ of energy to the lamp. Calculate:

(b) How much energy each coulomb of charge transfers to the lamp

A lamp is operated for $20 \mathrm{s}$. The current in the lamp is $10 \mathrm{A}$. In this time, it transfers $400 \mathrm{J}$ of energy to the lamp. Calculate:

(c) The p.d. across the lamp.

A small immersion heater is connected to a power supply of e.m.f. of $12 \mathrm{V}$ for a time of $150 \mathrm{s}$. The output power of the heater is $100 \mathrm{W}$. What charge passes through the heater?

(A) $1.4\mathrm{C}$

(B) $8.0\mathrm{C}$

(C) $1250\mathrm{C}$

(D) $1800\mathrm{C}$