David Sang and Graham Jones Solutions for Chapter: Electric Current, Potential Difference and Resistance, Exercise 6: Questions

A car headlamp bulb has a resistance of $36\Omega$. Calculate the current in the lamp when connected to a $\text{'}12\mathrm{V}\text{'}$ battery.

You can buy lamps of different brightness to fit in light fittings at home (Figure). A $100$ watt lamp glows more brightly than a $60$ watt lamp. Explain which of the lamps has the higher resistance.

(a ) Calculate the potential difference across a motor carrying a current of $1.0 \mathrm{A}$ and having a resistance of $50\Omega$.

(b) Calculate the potential difference across the same motor when the current is doubled. Assume its resistance remains constant.

Calculate the resistance of a lamp carrying a current of $0.40 \mathrm{A}$ when connected to a $230 \mathrm{V}$ supply.