﻿ In Thomson’s experiment for determining , the potential difference between the cathode and the anode (in the accelerating column) is the same as that between the deflecting plates (in the region of crossed fields). If the potential difference is doubled, by what factor should the magnetic field be increased to ensure that the electron beam remains undeflected?  : Kaysons Education

# In Thomson’s Experiment For determining , The Potential Difference Between The Cathode And The Anode (in The Accelerating column) Is The Same As That Between The Deflecting Plates (in The Region Of Crossed Fields). If The Potential Difference Is Doubled, By What Factor Should The Magnetic Field Be Increased To Ensure That The Electron Beam Remains Undeflected?

#### Video lectures

Access over 500+ hours of video lectures 24*7, covering complete syllabus for JEE preparation.

#### Online Support

Practice over 30000+ questions starting from basic level to JEE advance level.

#### National Mock Tests

Give tests to analyze your progress and evaluate where you stand in terms of your JEE preparation.

#### Organized Learning

Proper planning to complete syllabus is the key to get a decent rank in JEE.

#### Test Series/Daily assignments

Give tests to analyze your progress and evaluate where you stand in terms of your JEE preparation.

## Question

### Solution

Correct option is

The charge to mass ratio of an electron is given by

Where V is the accelerating voltage between cathode and anode. Let d be the separation between the deflecting plates. Now potential difference between the plates equals accelerating voltage V

Hence the electric field between the plates is

Using (ii) in (i) we get

If V is charged to V’ = 2VB must be increased to B’ given by

#### SIMILAR QUESTIONS

Q1

In a cathode ray tube, the electrons are subjected to a potential difference of 182 V. The maximum speed acquired by the electrons is

Q2

Electrons are projected with a velocity of  at right angles to a magnetic field of . If the radius of the circular path of electrons is 1 cm, what is the specific charge (charge to mass ratio) of electrons?

Q3

A proton projected with a velocity v describes a circle of radius r in a uniform magnetic field. With what velocity should an alpha-particle be projected so that it describes a circle of the same radius r in the same magnetic field?

Q4

A proton projected with kinetic energy K describes a circle of radius r in a uniform magnetic field. With what kinetic energy should an -particle be projected in the same magnetic field so that it describes a circle of radius 2r?

Q5

A proton and an -particle projected with equal linear momenta describe circular paths of radii r1 and r2 respectively in a uniform magnetic field. The ratio  is

Q6

An -particle and a deuteron projected with equal kinetic energies describe circular paths of radii r1 and r2 respectively in a uniform magnetic field. The ratio  is

Q7

In a cyclotron the speed of a charged particle is increased by

Q8

A monoenergetic electron beam with electron speed of  is subjected to a magnetic field of  normal to the beam velocity. What is the radius of the circular path traced by the beam? Given .

Q9

Two parallel plates are placed 5 cm apart in an evacuated tube and a potential difference of 200 V is applied across them. What is the force experienced by an electron at rest in the region between the plates?

Q10

In Millikan’s oil drop experiment, a charged oil drop of mass  is held stationary between two parallel plates 6 mm apart by applying a potential difference of 1200 V between them. How many excess electrons does the oil drop carry? Take g = 10 ms–2.