Question

Paper 27 Magnetism 1. Find the magnetic field at the point O, if the current is I A and R-20 cm. 100 2. The two long straight wires each carry a current of 1-5 A in opposite directions and are separated by a distance d 30 cm. Find the magnetic field a distance 1- 20 cm to the right of t wire on the right. 3. A single-turn, circular loop of radius 10 cm is to produce a field at its center that will just cancel the earth's magnetic field at the equator, which is 7 10-5 T directed north. Find the current in the loop and make a sketch showing the orientation of the loop and the current. 4. A beam of protons moves in a circle of radius 0.25 m. The beam moves perpendicular to a 0.3 T magnetic field. (a) What is the speed of each proton? (b) Determine the cyclotron / 2RXtR he 0 frequency of the protons. () Determine the magnitude of the centripetal force on each 5. A 100 mT magnetic field passes normally through a square loop of side 20 cm. The field proton becomes zero in 0.01 s. Calculate the magnitude of induced emf

***only the first question should be solved***

Answer 1

1 )

given I = 100 A ,

R = 20 cm

= 0.2 m

the magnetic field is B = ?

using equation B = $\mu$_o I / 2 R

= 4 x 3.14 x 10^-7 x 100 / 2 x 0.2

= 4 x 3.14 x 10^-5 / 2 x 0.2

= 2 x 3.14 x 10^-5 / 0.2  

= 3.14 x 10^-5 / 0.1   

B = 3.14 x 10^-4 T

B = 0.314 x 10^-3 T

or

so the magnetic field is B = 0.314 mT