# OPTICS+MAGNETISM+ELECTRICITY=MY PRobLEM

**Electricity and Magnetism**Level 3

sorry, for earlier one try it...

A negatively charged particle having a magnitude of charge q=0.1 C and mass, m=200 gm moves with a speed of 10 m/s enters a region of magnetic field B=4 T making an angle of 60 degree with X-axis. the direction of magnetic field is out of X-Y plane. A convex lens is placed at a distance of 14.3 m from the origin.region of magnetic field starts from the origin and extends till lens. Focal length of lens is 50 cm. Take X-axis as principle focus.

Now answer the following questions. 1. The radius of the path of charge is-:

a.) 4.25 m b.)6 m c) 5 m d) 7.1 m

2.find the frequency of revolution-:

a)0.32 Hz b)0.64 Hz c)2.16 Hz d)3.14 Hz

3.Change in momentum from t=-0 to t=pi/6 seconds is-:

a) 8 kg m/s b)2 kg m/s c)10 kg m/s d)17.32 kg m/s

4.Image height at t=pi/6 sec from principal axis.

a) 7.5 cm b)13 cm c)4.5 cm d) 9 cm

- find minimum value of initial velocity of charge so that image formed is virtual

a)7.2 m/s b)14.8 m/s c)16.4 m/s d)20 m/s