Quelpr
2 marksElectric Fields

CAPE Physics Unit 2 · 2013 · Paper 2 · Question 4(a)(i)

Figure 3 shows a model of an electron gun accelerating electrons through a potential difference V_p.

By equating the gain in kinetic energy of the electrons to the work done in accelerating them, show that the velocity, v_e, of the emerging beam electrons is given by v_e = sqrt((2 e V_p) / m_e).

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 4(a)(ii)Calculate the velocity of the electrons in the emerging electron beam when V_p = 25 kV.[2 marks]
  2. 4(b)(i)Calculate the magnitude and direction of the magnetic field inside the solenoid.[3 marks]
  3. 4(b)(ii)a)Explain the effect on the electron's horizontal velocity component, resulting from its interaction with the B-field.[2 marks]
  4. 4(b)(ii)b)Describe the effect on the electron's vertical velocity component.[2 marks]
  5. 4(b)(ii)c)Describe the resultant motion of the electrons and the nature of the image produced on the phosphorescent screen when the B-field is large enough to prevent…[4 marks]

More practice: the rest of this paper · more Electric Fields questions · all CAPE Physics Unit 2 past papers