A battery supplies a current of $1.25 \mathrm{A}$ to a circuit. Calculate how long it will take for $75 \mathrm{C}$ of charge to flow round the circuit.

A battery supplies a current of $1.25 \mathrm{A}$ to a circuit. If this battery has a capacity of $10 \mathrm{Ah}$, calculate how long can it supply this current.

During a journey in a car, the potential difference of $500 \mathrm{V}$ builds up, due to the static charge on the car caused by friction. A charge of $500 \mathrm{mC}$ is stored on the car. When the driver gets out and touches the car, this charge passes through the driver in $0.1 \mathrm{s}$. By calculating the current, explain why this $500 \mathrm{V}$ potential difference is not lethal(will cause death), but the mains potential difference is.

We say that an ohm $\left(\mathrm{\Omega }\right)$ is a volt $\left(\mathrm{V}\right)$ per ampere $\left(A\right)$. So, if a resistor has a resistance of $10 \Omega$, it takes $10 \mathrm{V}$ to make a current of $1 \mathrm{A}$ to flow through it. Calculate the voltage needed to make a current of $2 \mathrm{A}$ to flow through the same $10 \mathrm{\Omega }$ resistor.

We say that an ohm $\left(\Omega \right)$ is a volt $\left(V\right)$ per ampere $\left(A\right)$. So, if a resistor has a resistance of $10 \Omega$, it takes $10 \mathrm{V}$ to make a current of $1 \mathrm{A}$ flow through it.  Calculate the voltage needed to make a current of $1 \mathrm{A}$ to flow through a $20 \Omega$ resistor.

The current in a circuit changes as the resistance in the circuit changes. Complete the table by indicating whether the change indicated will cause the current to increase or decrease.

Use the equation $R=\frac{V}{I}$ to calculate the resistance of a lamp if a potential difference of $36 \mathrm{V}$ applied across it causes a current of $4.5 \mathrm{A}$ to flow through it.

How does doubling the length of a wire change its resistance?

How does doubling the diameter of a wire affect its resistance?