مهندس_فيزيائي
10-27-2006, 01:59 AM
السلام عليكم ورحمه الله وبركاته
مسالتين اشتغلت فيهم وما اعرف هل الجواب لها صحيح ام لا ولكن رسمة السؤال الثاني لم اعرف كيف ستكون ولكن نعلم انه اذا نقص التيار سيقل الجهد المكثف وهذا يدل على انهم سيكون متوازين مع بعض هذا والله اعلم
A coil of 50 turns and area 0.004m2 is situated in a region of uniform magnetic field B of magnitude 0.7T. the coil is rotated rapidly in a time 0.3s from a position with its normal at 45º to B, to a position with its normal at 70º to B. what is the average emf induced in the coil during this rotation?
Solution:
Flux Ø=BA cos (θ)= 0.7 x 0.004 x cos 45 = 0.002 T m2 this for initial flux
Flux Ø=BA cos (θ)= 0.7 x 0.004 x cos 70 = 0.001 T m2 this for second flux
Ư= initial flux- second flux= 0.002-0.001=0.001 ( average flux)
E=emf= -∆Ø/∆t=-0.001/0.3=-0.003 v/m
2- A long solenoid has a cross-sectional radius of 0.12m. the current in the windings is gradually decreased causing the magnetic field to decrease at a rate of 6.5 T/s. calculate the magnitude of the induced electric field at a distance of a) 0.04m and b) 0.2m from the axis of the solenoid. Draw a diagram to show the relative direction of these induced fields compared with the current in the windings.
Solution:
E= where is R is cross sectional radius
At r=0.04 m,
E=
At r= 0.2m
E=
As the distance go away further from the axis of the solenoid the induced electric field decreased so form the q we see that magnetic field decreased as well by the rate 6.5 T/s.
مسالتين اشتغلت فيهم وما اعرف هل الجواب لها صحيح ام لا ولكن رسمة السؤال الثاني لم اعرف كيف ستكون ولكن نعلم انه اذا نقص التيار سيقل الجهد المكثف وهذا يدل على انهم سيكون متوازين مع بعض هذا والله اعلم
A coil of 50 turns and area 0.004m2 is situated in a region of uniform magnetic field B of magnitude 0.7T. the coil is rotated rapidly in a time 0.3s from a position with its normal at 45º to B, to a position with its normal at 70º to B. what is the average emf induced in the coil during this rotation?
Solution:
Flux Ø=BA cos (θ)= 0.7 x 0.004 x cos 45 = 0.002 T m2 this for initial flux
Flux Ø=BA cos (θ)= 0.7 x 0.004 x cos 70 = 0.001 T m2 this for second flux
Ư= initial flux- second flux= 0.002-0.001=0.001 ( average flux)
E=emf= -∆Ø/∆t=-0.001/0.3=-0.003 v/m
2- A long solenoid has a cross-sectional radius of 0.12m. the current in the windings is gradually decreased causing the magnetic field to decrease at a rate of 6.5 T/s. calculate the magnitude of the induced electric field at a distance of a) 0.04m and b) 0.2m from the axis of the solenoid. Draw a diagram to show the relative direction of these induced fields compared with the current in the windings.
Solution:
E= where is R is cross sectional radius
At r=0.04 m,
E=
At r= 0.2m
E=
As the distance go away further from the axis of the solenoid the induced electric field decreased so form the q we see that magnetic field decreased as well by the rate 6.5 T/s.