Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

In a vacuum, two vertical metal plates are spaced a distance $d$ apart, as illustrated in Fig. 7.1. The potential difference (p.d.) across the plates is $V$. A nucleus with charge $+q$ starts from rest on plate X. The uniform electric field then accelerates the nucleus from plate X along a horizontal path to plate Y.
(a(i))[1]

State an expression, in terms of some or all of $d$, $q$ and $V$, for the magnitude of the electric field strength.

(a(ii))[1]

State an expression, in terms of some or all of $d$, $q$ and $V$, for the magnitude of the electric force acting on the nucleus.

(a(iii))[1]

State an expression, in terms of some or all of $d$, $q$ and $V$, for the kinetic energy of the nucleus when it reaches plate Y.

(b(i))[1]

State the change, if any, in the kinetic energy of the nucleus on reaching plate Y when the distance $d$ is halved, but the p.d. $V$ remains the same.

(b(ii))[1]

State the change, if any, in the kinetic energy of the nucleus on reaching plate Y when the nucleus is replaced by a different nucleus that is an isotope of the original nucleus with fewer neutrons.

(c(i))[1]

The nucleus is carbon-14 $^{14}_{6}\text{C}$. This nucleus decays to form a new nucleus by emitting a $\beta^-$ particle and one further particle of negligible mass. Calculate the nucleon number and the proton number of the new nucleus.

(c(ii))[1]

State the name of the particle with negligible mass.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Electric field strength, $E = \frac{V}{d}$

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