Verified Solution • 2025–26 Session moderate

QJEEAdv24Ph75c2: JEE Advanced 2024 Physics - Class 12 JEEAdv24Ph75c2 Solution: A positive, singly ionized atom of mass number is accelerated…

A positive, singly ionized atom of mass number AMA_{\mathrm{M}} is accelerated from rest by the voltage 192 V192 \mathrm{~V} . Thereafter, it enters a rectangular region of width ww with magnetic field B⃗0=0.1k^\vec{B}_0=0.1 \hat{k} Tesla, as shown in the figure. The ion finally hits a detector at the distance xx below its starting trajectory.

[Given: Mass of neutron/proton =(5/3)×10−27 kg=(5 / 3) \times 10^{-27} \mathrm{~kg} , charge of the electron =1.6×10−19C=1.6 \times 10^{-19} \mathrm{C} .]

JEE Advanced 2024 Paper 2 Online Physics - Magnetism Question 1 English

Which of the following option(s) is(are) correct?

Multiple Choice Options

  • A The value of xx for H+H^{+} ion is 4 cm4 \mathrm{~cm} .
  • B The value of xx for an ion with AM=144A_{\mathrm{M}}=144 is 48 cm48 \mathrm{~cm} .
  • C For detecting ions with 1≤AM≤1961 \leq A_{\mathrm{M}} \leq 196 , the minimum height (x1−x0)\left(x_1-x_0\right) of the detector is 55 cm55 \mathrm{~cm} .
  • D The minimum width ww of the region of the magnetic field for detecting ions with AM=196A_{\mathrm{M}}=196 is 56 cm56 \mathrm{~cm} .

Step-by-Step Verified Solution

JEE Advanced 2024 Paper 2 Online Physics - Magnetism Question 1 English Explanation

amp;x=2Ramp;⇒x=2PqB⇒x=22mqVqB⇒x=2B2mVq\begin{aligned}& x=2 R \\& \Rightarrow x=2 \frac{P}{q B} \Rightarrow x=\frac{2 \sqrt{2 m q V}}{q B} \Rightarrow x=\frac{2}{B} \sqrt{\frac{2 m V}{q}}\end{aligned}

Option A

For H+→m=53×10−27 kg\mathrm{H}^{+} \rightarrow \mathrm{m}=\frac{5}{3} \times 10^{-27} \mathrm{~kg}

∴x=20.12×53×10−27×1921.6×10−19=4 cm\therefore x=\frac{2}{0.1} \sqrt{\frac{2 \times \frac{5}{3} \times 10^{-27} \times 192}{1.6 \times 10^{-19}}}=4 \mathrm{~cm}

Option B

For Am=144\mathrm{A}_{\mathrm{m}}=144

x=20.12×144×53×10−27×1921.6×10−19=48 cmx=\frac{2}{0.1} \sqrt{\frac{2 \times 144 \times \frac{5}{3} \times 10^{-27} \times 192}{1.6 \times 10^{-19}}}=48 \mathrm{~cm}

Option C

for Am=1\mathrm{A}_{\mathrm{m}}=1

x=4 cm\mathrm{x}=4 \mathrm{~cm} & for Am=196\mathrm{A}_{\mathrm{m}}=196

x=56 cm\mathrm{x}=56 \mathrm{~cm} .

so x0=4 cm\mathrm{x}_0=4 \mathrm{~cm} & x1=56 cm\mathrm{x}_1=56 \mathrm{~cm}

∴x1−x0=52 cm\therefore \mathrm{x}_1-\mathrm{x}_0=52 \mathrm{~cm} .

Option D

Minimum width =R=\mathrm{R}

for AM=196\mathrm{A}_M=196

R=PqB=2mqVqB\mathrm{R}=\frac{\mathrm{P}}{\mathrm{qB}}=\frac{\sqrt{2 \mathrm{mqV}}}{\mathrm{qB}}

R=1 B2mVq\mathrm{R}=\frac{1}{\mathrm{~B}} \sqrt{\frac{2 \mathrm{mV}}{\mathrm{q}}}

wmin⁡=R=10.12×196×53×10−27×1921.6×10−19=28 cm\mathrm{w}_{\min }=\mathrm{R}=\frac{1}{0.1} \sqrt{\frac{2 \times 196 \times \frac{5}{3} \times 10^{-27} \times 192}{1.6 \times 10^{-19}}}=28 \mathrm{~cm}

Related Learning Resources & Exam Preparation