A $20 cm$ length of wire is placed at right angles to a magnetic field. When a current of $1.5$ A flows in the wire, a force of $0.015$ $N$ acts on it. Determine the flux density of the field .

A wire of length$50 cm$  carrying a current lies at right angles to a magnetic field of flux density$5.0mT.$

(a) If${10}^{18}$electrons pass a point in the wire each second, what current is flowing? (electron chargee $=1.60\times 10-19 C.$)

A wire of length $50cm$ carrying a current lies at right angles to a magnetic field of flux density$5.0mT.$ What force acts on the wire?

In the examples shown in the diagrams in Figure, which current balances will tilt? Will the side carrying the current tilt upwards or downwards?

Four current balances- will they tip?

In the arrangement shown in Figure, the balance reading changes from 1$102.48 g$ to $104.48 g$ when the current is switched on. Explain why this happens and give the direction and the size of the force on the wire when the current is on. What is the direction of the current in the wire?

Using an electronic balance.

The coil of an electric motor is made up of $200$ turns of wire carrying a current of $1.0A$ The coil is square, with sides of length $20cm,$, and it is placed in a magnetic field of flux density $0.05T.$

In what position must the coil be for this force to have its greatest turning effect?

What force is exerted on each of the currents shown in Figure, and in what direction does each force act?

Three currents in a magnetic field.