Resistance of the galvanometer coil is given as $G=12 \Omega$ Current for which there is full scale deflection is given as I $=3 \mathrm{~mA}$ To convert a galvanometer to voltmeter,a resistor with...
A galvanometer coil has a resistance of 
and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?
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long and of radius, 
has 3 layers of windings of 300 turns each. A 
long wire of mass 
lies inside the solenoid (near its centre) normal to its axis; both the wire and the axis of the solenoid are in the horizontal plane. The wire is connected through two leads parallel to the axis of the solenoid to an external battery which supplies a current of 
in the wire. What value of current (with an appropriate sense of circulation) in the windings of the solenoid can support the weight of the wire? 
.
is placed in a uniform magnetic field of 
normal to the plane of the coil. If the current in the coil is 
, what is the average force on each electron in the coil due to the magnetic field? (The coil is made of copper wire of cross-sectional area 
, and the free electron density in copper is given to be about 
is established along the positive z-direction. A rectangular loop of sides 
carries a current of 
What is the torque on the loop in the different cases shown in the figure? What is the force on each case? Which case corresponds to stable equilibrium?
exists in a cylindrical region of a radius of 
, its direction parallel to the axis along east to west. A wire carrying a current of 
A in the north to south direction passes through this region. What is the magnitude and direction of the force on the wire if, (a) the wire intersects the axis, (b) the wire is turned from N-S to the northeast-northwest direction
(for a short time). What is the force per unit length between the wires if they are 
long and 
apart? Is the force attractive or repulsive?
and mass 
is suspended by two vertical wires at its ends. A current of 
.
) is uniform in a small region and has a magnitude of 
. In the same region, a uniform electrostatic field is maintained in a direction normal to the common axis of the coils. A narrow beam of (single species) charged particles all accelerated through 
enters this region in a direction perpendicular to both the axis of the coils and the electrostatic field. If the beam remains undeflected when the electrostatic field is 
, make a simple guess as to what the beam contains. Why is the answer not unique?
, enters a region with a uniform magnetic field of 
. Determine the trajectory of the electron if the field (a) is transverse to its initial velocity, (b) makes an angle of 
with the initial velocity.
and 
turns carrying current 
, the magnitude of the magnetic field at a point on its axis at a distance 
from its centre is given by, 
(a) Show that this reduces to the familiar result for field at the centre of the coil. (b) Consider two parallel co-axial circular coils of equal radius 
, and number of turns 
, carrying equal currents in the same direction, and separated by a distance 
Show that the field on the axis around the mid-point between the coils is uniform over a distance that is small as compared to 
, approximately.
with the normal of the coil. To prevent the coil from turning, determine the magnitude of the counter-torque that must be applied. (b) Would your answer change, if the circular coil in (a) were replaced by a planar coil of some irregular shape that encloses the same area? (All other particulars are also unaltered.)
and outer radius 
, around which 3500 turns of a wire are wound. If the current in the wire is 
, what is the magnetic field?(a) outside the toroid, (b) inside the core of the toroid
m2. The maximum current-carrying capacity of a given coil of wire is 15 A and the number of turns per unit length that can be wound around a core is at most 1000 turns 
. Suggest some appropriate design particulars of a solenoid for the required purpose. Assume the core is not ferromagnetic.
m
normal to the field. Find the frequency of revolution of the electron in its circular orbit. Does the answer depend on the speed of the electron? Explain.
T) is maintained. An electron is shot into the field with a speed of 
normal to the field. Explain why the path of the electron is a circle. Determine the radius of the circular orbit.