Advertisements
Advertisements
Question
A conducting rod held horizontally along East- West direction is dropped from rest from a certain height near the Earth’s surface. Why should there be an induced emf across the end of the rod? Draw a plot showing the instantaneous variation of emf as a function of time from the instant it begins to fall.
Solution
Emf induced due to change of magnetic flux across rod due to the presence of Earth’s magnetic field.
We know,
`E =(dphi_B)/(dt)`
As the Earth’s magnetic field is uniform,
`E =-Blv = -Bl (dx)/(dt)`
Hence,
RELATED QUESTIONS
The horizontal component of the earth’s magnetic field at a place is B and angle of dip is 60°. What is the value of vertical component of earth’s magnetic field at equator?
What is the angle of dip at a place where the horizontal and vertical components of the Earth’s magnetic field are equal?
Can the dip at a place be (a) zero (b) 90°?
Choose the correct option.
A place where the vertical components of Earth's magnetic field is zero has the angle of dip equal to
Answer the following question in detail.
How does the magnetic declination vary with latitude? Where is it minimum?
Answer the following question regarding earth’s magnetism:
In which direction would a compass free to move in the vertical plane point to, if located right on the geomagnetic north or south pole?
A short bar magnet of magnetic moment 5.25 × 10−2 J T−1 is placed with its axis perpendicular to the earth’s field direction. At what distance from the centre of the magnet, the resultant field is inclined at 45° with earth’s field on (a) its normal bisector and (b) its axis. Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.
The small angle between magnetic axis and geographic axis at a place is ______.
Assertion(A): A magnetic needle free to rotate in a vertical plane, orients itself (with its axis) vertical at the poles of the earth.
Reason (R): At the poles of the earth the horizontal component of earth’s magnetic field will be zero.
Select the most appropriate answer from the options given below:
Assume the dipole model for earth’s magnetic field B which is given by BV = vertical component of magnetic field = `mu_0/(4pi) (2m cos theta)/r^3` BH = Horizontal component of magnetic field = `mu_0/(4pi) (sin theta m)/r^3` θ = 90° – lattitude as measured from magnetic equator. Find loci of points for which (i) |B| is minimum; (ii) dip angle is zero and (iii) dip angle is ± 45°.
