(a) State Faraday's law of electromagnetic induction.

 

(b) A circular coil of diameter $200mm$ has $600$ turns is shown. It is placed with its plane perpendicular to a horizontal magnetic field of uniform flux density $50mT.$. The coil is then rotated through $90°$ about a vertical axis in a time of$120ms$

(i) the magnetic flux passing through the coil before the rotation

(b) A circular coil of diameter $200mm$ has $600$ turns is shown. It is placed with its plane perpendicular to a horizontal magnetic field of uniform flux density $50mT.$. The coil is then rotated through $90°$ about a vertical axis in a time of$120ms$

(ii) the change of magnetic flux linkage produced by the rotation

(b) A circular coil of diameter $200mm$ has $600$ turns is shown. It is placed with its plane perpendicular to a horizontal magnetic field of uniform flux density $50mT.$. The coil is then rotated through $90°$ about a vertical axis in a time of$120ms$

(iii) the average magnitude of the induced e.m.f. in the coil during the rotation.

A bicycle wheel is mounted vertically on a metal axle in a horizontal magnetic field, as shown in the diagram. Sliding connections are made to the metal edge of the wheel and to the metal axle.

(a) (i) Explain why an e.m.f. is induced when the wheel rotates.

A bicycle wheel is mounted vertically on a metal axle in a horizontal magnetic field, as shown in the diagram. Sliding connections are made to the metal edge of the wheel and to the metal axle.

(a) (ii) State and explain two ways in which this e.m.f. can be increased.

A bicycle wheel is mounted vertically on a metal axle in a horizontal magnetic field, as shown in the diagram. Sliding connections are made to the metal edge of the wheel and to the metal axle.

(b) The wheel rotates five times per second and has a radius of $15 \mathrm{cm}.$ The magnetic flux density may be assumed to be uniform and of value $5.0\times {10}^{-3}$ $T.$

(i) the area swept out each second by one spoke

A bicycle wheel is mounted vertically on a metal axle in a horizontal magnetic field, as shown in the diagram. Sliding connections are made to the metal edge of the wheel and to the metal axle.

(b) The wheel rotates five times per second and has a radius of $15 \mathrm{cm}$ The magnetic flux density may be assumed to be uniform and of value $5.0\times {10}^{-3}$ $T.$

(ii) the induced e.m.f. between the contacts.