Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Medical
  • A cathode ray tube contains a pair of parallel metal plates apart and <img alt="3.5cm" src="https://entrancecorner.on

A cathode ray tube contains a pair of parallel metal plates 2.0cm apart and 3.5cm long. A narrow horizontal beam of electrons with velocity of 3 \times 10^7 \mathrm{~ms}^{-1} is poured down the tube midway between the two plates. When the potential difference of 670 \mathrm{~V} is maintained across the plates, it is found that the electron beam is so deflected that it just strikes the end of one of the plates. Find the specific charge of an electron.

Option: 1

2.2 \times 10^{11} \mathrm{~kg}^{-1}


Option: 2

3.1 \times 10^{-8} \mathrm{~kg}^{-1}


Option: 3

2.9 \times 10^{7} \mathrm{~kg}^{-1}


Option: 4

4.1 \times 10^{-6} \mathrm{~kg}^{-1}


Answers (1)

best_answer

\begin{aligned} & y=\frac{1}{2} \mathrm{~cm}=0.5 \times 10^{-2} \mathrm{~m} \\ & l=3.5 \times 10^{-2} \mathrm{~m} \\ & v=3 \times 10^7 \mathrm{~ms}^{-1} \quad \mathrm{~V}=670 \mathrm{~V} \\ & d=2 \mathrm{~cm}=2 \times 10^{-2} \mathrm{~m} \end{aligned}

Time to cross the tube,

t=\frac{l}{v}=\frac{3.5 \times 10^{-2}}{3 \times 10^7}=1.16 \times 10^{-9} \mathrm{~s}

\begin{aligned} y & =\frac{1}{2} a t^2=\frac{1}{2}\left(\frac{E_e}{m}\right) t^2 \\ & =\frac{1}{2} \frac{(v / d) e}{m} t^2 \end{aligned}

\frac{e}{m}=\frac{2 y d}{V t^2}=\frac{2 \times(0.5 \times 10^-^2) \times 2 \times 10^-^2 \mathrm{~m}}{670 \times\left(1.16 \times 10^{-9}\right)}

      \begin{aligned} & =\frac{2 \times 10^{-4}}{670 \times 1.3456 \times 10^{-18}} \\ & =0.0022 \times 10^{-4+18}=0.0022 \times 10^{14} \\ & =2.2 \times 10^{11} \mathrm{~kg}^{-1} \\ & \end{aligned}

Posted by

Riya

View full answer

NEET 2024 Most scoring concepts

    Just Study 32% of the NEET syllabus and Score up to 100% marks

Similar Questions

Trending Articles/News

anam-khan

NEET UG 2026 leak probe traces guess paper trail from Kerala student to Rajasthan network
anam-khan

'Replace NTA': FAIMA files plea in SC over NEET UG 2026 paper leak
anam-khan

NEET UG 2026 Paper Leak LIVE: Protests erupt across states, paper leak probe expands; re-NEET date soon

Latest Question