Class 12th Physics

A proton, a deutron and an alpha particle with the same kinetic energy enter a region of uniform magnetic field, moving at right angles to B. The radii of their circular paths are in the ratio :

       

• (a) 1: 1 :1

• (b) 1 :√2:1

• (c) 1 : √2: √2

• 1 : √2: 2

A charged particle of mass m and charge q enters a magnetic field B with a velocity v at an angle θ with the direction of B. The radius of the resulting path is

        

• mnsinθ/qB

• mn/qBsinθ

• mv/qB

• mvtanθ/qB

A positively charged particle with charge q is moving in a uniform electromagnetic field. Electric and magnetic field are along same direction. If angle between the fields and initial direction of motion is θ= π/2, then its path will be

              

• (a) helical with increasing pitch and constant time period   

• (b) helical with increasing pitch and decreasing time period

• (c) helical with constant pitch and time period

•   (d) helical with increasing pitch and time period

A 0.5 m long straight wire in which a current of 1.2A is kept at right angle to a uniform magnetic field of 2.0 tesla. The force acting on the wire will be

       

• (a) 2N

•    (b) 2.4N

• (c) 1.2N    

• (d) 3N

A ring of charge Q and radius R is revolved about an axis passing through its centre and perpendicular to plane with angular velocity ω. Magnetic induction at centre of ring is

   

• (a) 0

• (b) μ0Qω/2πR

• (c) μ0Qω/4πR

• (d) μ0QωR/2π

 The magnetic force on a charged particle is always perpendicular to its velocity

 

•    (a) the magnetic force can change the velocity of the particle

•   (b) the magnetic force can change the speed of the particle

•    (c) the magnetic force can change both         

• (d) the magnetic force can change neither.

A deuteron moving along the x-y plane in a uniform magnetic field experiences a force in the – ve z direction. If it moved along the positive z direction, the force acting on it -

           

•   (a) would be zero  

•   (b) could be along y-axis

•    (c) would be along x - axis   

• (d) none

               A positively charged particle with charge q is moving in a uniform magnetic field. If angle between the magnetic field and direction of motion is θ=π/2, then its path will be

           

•   (a) circular

• (b) straight line

• (c) helical

• (d) parabolic

A proton, a deuteron and an α-particle are accelerated through the same potential difference and then they enter in a uniform normal magnetic field. The ratio of their time period of circular path is

• 1: √2:√8

• 1: √2: 2

• √2:√2:1

• 1:2: 2

The magnetic field outside a long solenoid is

        

• (a) infinite

•    (b) Zero

• (c) Uniform

• (d) Non-uniform