Electromagnetic theory

Skin depth is

• a skin infection at a depth

• a skin etching

• loss of electromagnetic waves in free space

• Exponential decay of electromagnetic signal in a medium

Maxwell's 4th equation in charge free steady current free space suggests

• Magnetic field can be produced even if no current element is present due to spacial variation in electric field

• Electric field can be produced even if no current element is there

• Time variation of electric field can produce magnetic field even if no current density is there

• Time variation of magnetic field can produce electric field even if no charge density is there

Speed electromagnetic wave in a medium is

• sqrt(mu0*epsilon0)

• 1/sqrt(mu0*epsilon0)

• 1/sqrt(mu*esilon)

• sqrt(mu*esilon)

A rectangular loop of sides 0.08 m and 0.02 cm having a resistance 1.6 ohm is placed in a magnetic field of 0.3 T directed normal to the loop. The magnetic field is gradually reduced to 0.02 T/sec. Then induced current using the formula e=-dphi/dt. I=e/R and phi=area*magnetic field is

• e= 3.2×10-5 V, I=2 x 10-5 A

• e= 3.2×10-1 V, I=2 x 10-1 A

• e= 3.2 V, I=2 A

• e=2 x 10-4 V and I= 3.2 x10-4 A

A metal bar slides without friction on two parallel conducting rails at distance l apart. A resistor R is connected across the rails and a uniform magnetic field B, pointing into this plane fils the entire region. If the bar moves to the right at a constant speed v then the current through the resistor using the formula e=-dphi/dt, phi= Area * magnetic field, i=e/R

• e= B dA/dt, i=Blv/R

• e= A dB/dt, i=Blx/R

• e= -B dA/dt, i= Blv/R

• |e|= B dA/dt, i= Blv/R

If E and B of an electromagnetic wave travelling through a free space is of propagation vector k then

• k.E=0

• k x E =0

• B x E =0

• k x E = --B

The magnetic flux linked with a coil at any instant t is given by phi= 5t3 -100 t + 200, the emf induced in the colil at t=2 sec

• 200 V

• 40 V

• 20 V

• -20V

If mu= 1.732 then determine angle of polarization

• 30

• 60

• 90

• infinity

In Nicol Prism has canada balsum layer

• to eliminate O-ray

• to eliminate e-ray

• to eliminate o and e ray both

• to reduce headache

Double refraction takes place in

• anisotropic crystal only

• isotropic crystal only

• in any crystal

• all types of crystal