Question
A proton and an $\alpha$-particle are accelerated from rest through the same potential difference. Compare their final speeds. Charge on an $\alpha$-particle $=2 \times$ charge on a proton, mass of an $\alpha$ particle $=4 \times$ mass of a proton.

Answer

Lution: Let $q _1=$ charge on an $\alpha$-partic $1 e , q _2=$ charge on a proton, $m _1=$ mass of an $\alpha$-particle, $m_2=$ mass of a proton, $v_1=$ final speed of the $\alpha$-particle, $v_2=$ final speed of the proton
$
\therefore \frac{q_1}{q_2}=2 \text { and } \frac{m_1}{m_2}=4 \quad \therefore \frac{m_2}{m_1}=\frac{1}{4}
$
If the particles are accelerated from rest, through a potential difference $V$,
$
\begin{aligned}
& \frac{1}{2} m_1 v_1^2=q_1 V \text { and } \frac{1}{2} m_2 v_2^2=q_2 V \\
\therefore & \frac{m_1 v_1^2}{m_2 v_2^2}=\frac{q_1}{q_2} \quad \text {} \\
\therefore & \frac{v_1^2}{v_2^2}=\frac{q_1}{q_2} \times \frac{m_2}{m_1}=2 \times \frac{1}{4}=\frac{1}{2} \\
\therefore & \frac{v_1}{v_2}=\frac{1}{\sqrt{2}}=0.707
\end{aligned}
$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

What do you do if your vehicle is trapped on a slippery or sandy road? What is the physics involved?
State the function of the shunt in modifying a galvonometer to an ammeter.
In Young's double slit experiment, the slits are \(0.5 mm\) apart and interference is observed on a screen placed at a distance of \(100 cm\) from the slit. It is found that 9 th bright fringe is at a distance of \(8.835 mm\) from the \(2^{\text {nd }}\) dark fringe, on the same side of the centre of the fringe pattern. Find the wavelength of light used.
The molar specific heat of nitrogen at constant volume is $4.952 \mathrm{cal} / \mathrm{mol} . \mathrm{K}$ and that at constant pressure is $6.933 \mathrm{cal} / \mathrm{mol} . \mathrm{K}$. Find the mechanical equivalent of heat. Take $R=8.31$ $\mathrm{J} / \mathrm{mol} . \mathrm{K}$.
From the definition of linear SHM, derive an expression for the angular frequency of a body performing linear SHM.
An alpha particle $($carrying a positive charge $q=3.2 \times 10^{-19} C )$ enters a region of uniform magnetic field of induction $\vec{B}=(0.5 \hat{ i }+\hat{ j }-\hat{ k })$ T with a velocity $\vec{v}=(4 \hat{ i }+4 \hat{ j }+\hat{ k }) \times 10^2\ m / s$. What is the force $\vec{F}$ on the alpha particle?
Define photoelectric effect and Explain the experimental set-up of photoelectric effect.
A parallel beam of monochromatic light is incident on a glass slab at an angle of incidence \(60^{\circ}\). Find the ratio of width of the beam in the glass to that in the air if refractive index of glass is \(\frac{3}{2}\).
Do we need a banked road for a two wheeler? Explain.
What should be the tension applied to a wire of length $1 m$ and mass $10 grams$, if it has to vibrate with the fundamental frequency of $50 Hz$ ?