This question is about the effect of fields on particles. 

Complete the table below to indicate which particles are effected by gravitational, magnetic and electric fields. 

The diagram below shows an electron travelling at speed 0.3c. As the electron enters the magnetic field it experiences a force causing it to follow a curved path.

State the direction of the magnetic field.

Explain why the electron follows a curved path as it enters the magnetic field. 

The magnetic field strength of the uniform field is 2 x 10^-2 T. 

Calculate the radius of the path taken by the electron as it travels through the magnetic field. 

The diagram below shows a current carrying conductor in a uniform magnetic field.

The 40 cm length of wire carries a current of 0.75 A, perpendicular to the magnetic field.

The strength of the magnetic field is 2.5 x 10^-2 T.

Calculate the force experienced by the current carrying conductor.

The current carrying conductor is rotated through 90° such that it runs parallel to the magnetic field. 

Describe how rotating the wire through 90° affects the force it experiences due to the magnetic field.

The principle of the motor effect can be used to create a moving-cone loudspeaker.

Explain how the moving-coil loudspeaker converts an electrical signal into a sound wave. 

This question is about the effect of magnetic fields on charged particles. 

Explain what is meant by a magnetic field. 

A particle has mass m, charge +Q and speed v. 

The particle enters a uniform magnetic field of flux density B such that on entry it is moving normal to the magnetic field. 

Derive an expression for the radius of the path followed by the charged particle. 

The particle described in part b has a charge of +2e and a mass of 6.68 x 10^-27 kg.

The charged particle follows a path of diameter 10 cm. The particle is travelling at 10% of the speed of light.

Calculate the magnetic flux density B of the magnetic field. 

Describe the effect of doubling the kinetic energy of the charged particle on the radius of the path taken. 

The diagram below shows a cyclotron. A proton is released from rest and is accelerated to high speeds using an electric field between the two horizontal 'dees'. A magnetic field acts vertically through the dees such that the charged particles follow a semicircular path through each dee.

The dees are connected to an alternating power supply. The power supply is adjusted so that the proton is always accelerated by the peak electric field as it crossed the gap between the dees. 

Explain why the proton follows a semicircular path while inside the dees.

The proton is accelerated by a peak accelerating potential of 9 kV. 

The proton travels across the gap 1300 times before leaving the cyclotron. 

Calculate the kinetic energy of the proton as it leaves the cyclotron. Give your answer in eV.

Calculate the velocity of the proton as it leaves the cyclotron.

The magnetic flux density of the magnetic field is 1.2 T. 

Calculate the radius of the dees used.

Two magnets, supported on a yoke are placed on a digital balance.

The diagram below shows the magnets viewed from above. 

Draw the magnetic field between the two magnets.

The copper wire is connected to a variable resistor and a cell of e.m.f. 10 V. The variable resistor is set to 100 $\Omega$ and the cell has an internal resistance of 0.6 $\Omega$. 

The total length of copper wire used is 40 cm. 

The resistivity of copper is 1.77 x 10^-8 $\Omega$ m.

The diameter of the copper wire is 1.2 mm.

Calculate the current in the copper wire when the switch is closed.

When there is no current flowing through the wire, the balance reads 125.4 g.

The switch is closed allowing a current to flow through the circuit. 

Explain what happens to the digital balance reading. 

The magnetic flux density B is 15 T. 

Calculate the mass reading shown when the switch is closed.

The diagram below shows an electron gun connected to an evacuated glass tube. 

Electrons are emitted by the filament and accelerated by a potential difference between the anode and filament. 

Describe how electrons are emitted from the filament.

The electrons are accelerated through a potential difference of 280 V. 

Calculate the speed of the electrons as they pass the anode.

When the electrons enter the uniform magnetic field they follow a circular path. 

The magnetic flux density of the magnetic field is 1.3 mT. 

Calculate the radius of the path taken by the electron. 

The accelerating voltage is doubled. 

Describe the effect on the radius of the path taken by the electron. 

Mass spectrometers are used to measure the mass of ions. 

State the direction of the force on a positive ion at A due to the magnetic field.

State the direction of the force on a negative ion at A due to the electric field.

The electric field strength E = 1.3 x 10⁴ V m^-1. 

B = 0.18 T

Calculate the speed at which the ions emerge from the aperture.

When the ions emerge from the aperture they experience another magnetic field of flux density 0.18T.

Draw the path of the positive ion as it passes through the small aperture.

The ion has a relative charge of +1 and a mass of 1.0 x 10^-26 kg.

Calculate the radius of the path drawn in part d).