Home
Class 11
PHYSICS
An electron and a proton are moving und...

An electron and a proton are moving under the influence of mutual forces . In calculating the change in the kinetic energy of the system during motion , one ignores the magnetic force of one on another . This is , because

A

the two magnetic forces are equal and opposite ,so they produce no net effect

B

the magnetic forces do not work on each particle

C

the magnetic forces do equal and opposite (but non -zero) work on each particle .

D

the magnetic forces are necessarily negligible .

Text Solution

Verified by Experts

The correct Answer is:
B

When electron and proton are moving under influence of their mutual forces , the magnetic forces are perpendicular to tem hence work done by these forces is zero .
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • WORK, ENERGY AND POWER

    KUMAR PRAKASHAN|Exercise SECTION - D NCERT Exemplar Solutions (Very Short Answer Type Questions)|12 Videos
  • WORK, ENERGY AND POWER

    KUMAR PRAKASHAN|Exercise SECTION - D NCERT Exemplar Solutions (Short Answer Type Questions)|10 Videos
  • WORK, ENERGY AND POWER

    KUMAR PRAKASHAN|Exercise SECTION - C Objective Questions (VSQs)|52 Videos
  • WAVES

    KUMAR PRAKASHAN|Exercise SECTION-F (Questions From Module) (Sample questions for preparation of competitive exams)|23 Videos

Similar Questions

Explore conceptually related problems

A particle is moving under the influence of a force which is fixed in magnitude and acting at an angle theta in the direction of motion. The path described by the particle is

Obtainwork energy theorem of a particle moving in one dimension under the variable force .

Knowledge Check

  • A proton is moving away from an electron, then find the change in potential energy of the system.

    A
    decreases
    B
    increases
    C
    remains constant
    D
    may decrease or increase
  • A moving electron approaches another electron. What would be the change in the potential energy of this system ?

    A
    Remains constant
    B
    Increases
    C
    Decreases
    D
    May increase or decrease
  • A proton is moving perpendicular to a uniform magnetic field of 2.5 tesla with 2MeV kinetic energy. The force on the proton is ______ .

    A
    `3xx10^(-10)N`
    B
    `8xx10^(-11)N`
    C
    `3xx10^(-11)N`
    D
    `8xx10^(-12)N`
  • Similar Questions

    Explore conceptually related problems

    The graph below shows how the force on a mass depends on the position of the mass. What is the change in the kinetic energy of the mass as it moves from x=0.0m to x=3.0 m ?

    Figure shows a metal rod PQ resting on the smooth rails AB and positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod =15 cm, B =0.50 T, resistance of the closed loop containing the rod 9.0 m Omega . Assume the field to be uniform. (a) Suppose K is open and the rod is moved with a speed of 12 "cm s"^(-1) in the direction shown. Give the polarity and magnitude of the induced emf. (b) Is there an excess charge built up at the ends of the rods when K is open ? What if K is closed ? (c) With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience magnetic force due to the motion of the rod. Explain. (d) What is the retarding force on the rod when K is closed ? How much power is required (by an external agent) to keep the rod moving at the same speed (= 12 cm s^(-1) ) when K is closed ? How much power is required when K is open? (f)How much power is dissipated as heat in the closed circuit ? What is the source of this power ? (g) What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular ?

    Two paricle A and B initially at rest, move towards each other under mutual force of attraction. At the instant when the speed of A is V and the speed of B is 2V, the speed of the centre of mass of the system is

    A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7N on a table with coefficient of kinetic friction = 0.1 . Compute the Change in kinetic energy of the body in 10s.

    If one were to apply Bohr model to a particle of mass 'm' and charge 'q' moving in a plane under the influence of a mgentic filed 'B' , the energy of the cahrged particle in the n^(th) level will be :-