CAIE A-Level Physics A2 22.1.4 The Electronvolt Ev As a Unit of Energy Questions

Practise converting particle and photon energies between electronvolts and joules, comparing magnitudes and retaining the correct energy unit.

Exam points

convert and use electronvolt as a unit of energy
compare photon or particle energies in eV and joules

[Maximum number: 2]

Electrons are accelerated from rest through a potential difference (p.d.) of 4.8 kV .

Show that the final speed of the electrons is $4.1 \times 10^{7} \mathrm{~m} \mathrm{~s}^{-1}$ .

$\frac{1}{2} m v^{2}=e V$ $1 / 2 \times 9.11 \times 10^{-31} \times v^{2}=1.60 \times 10^{-19} \times 4800 \mathrm{so} v=4.1 \times 10^{7} \mathrm{~m} \mathrm{~s}^{-1}$

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CAIE A-Level Physics A2 22.1.4 The Electronvolt Ev As a Unit of Energy Questions question 1