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Find the electric field of a potential function given by 20 log x + y at the point (1,1,0).
a Explanation: The electric field is given by E = -Grad(V). The gradient of the given function is 20i/x + j. At the point (1,1,0), we get 20i + j. The electric field E = -(20i + j) = -20i – j.
a
See lessExplanation: The electric field is given by E = -Grad(V). The gradient of the given
function is 20i/x + j. At the point (1,1,0), we get 20i + j. The electric field E = -(20i + j) = -20i – j.
Calculate the ratio of sine of incident angle to the sine of reflected angle when the refractive indices of medium 1 and 2 are given as 2.33 and 1.66 respectively.
a Explanation: The Snell law is given by N1 sin θi = N2 sin θt. To get sin θi/sin θt, the ratio is N2/N1. On substituting for N1 = 2.33 and N2 = 1.66, we get 1.66/2.33 = 0.71.
a
See lessExplanation: The Snell law is given by N1 sin θi = N2 sin θt. To get sin θi/sin θt, the ratio is N2/N1. On substituting for N1 = 2.33 and N2 = 1.66, we get 1.66/2.33 = 0.71.
The propagation of the electromagnetic waves can be illustrated by
c Explanation: By Flemming’s rule, when the thumb and the middle finger represent theinputs (say current and field respectively), then the fore finger represents the output (force, in this case). The EM propagation can be illustrated by this rule.
c
See lessExplanation: By Flemming’s rule, when the thumb and the middle finger represent theinputs (say current and field respectively), then the fore finger represents the output (force, in this case). The EM propagation can be illustrated by this rule.
Which components exist in an electromagnetic wave?
c Explanation: In an electromagnetic wave, the electric and magnetic components coexist.They propagate perpendicular to each other and to the direction of propagation in space.
c
See lessExplanation: In an electromagnetic wave, the electric and magnetic components coexist.They propagate perpendicular to each other and to the direction of propagation in space.
Find the time constant of a capacitor with capacitance of 2 microfarad having an internal resistance of 4 megaohm.
c Explanation: The time constant of capacitor is given by T = RC, where R = 4×106 and C= 2×10-6. Thus T = 4×106 x2x10-6 = 8 seconds.
c
See lessExplanation: The time constant of capacitor is given by T = RC, where R = 4×106 and C= 2×10-6. Thus T = 4×106 x2x10-6 = 8 seconds.
The gradient of the magnetic vector potential can be expressed as
a Explanation: The gradient of A is the ratio of the negative gradient of electric potential to the speed of light c. We can write c = 1/√(με). Thus grad(A) = -με dV/dt is the required expression.
a
See lessExplanation: The gradient of A is the ratio of the negative gradient of electric potential to the speed of light c. We can write c = 1/√(με). Thus grad(A) = -με dV/dt is the required expression.
When electric potential is null, then the electric field intensity will be
d Explanation: The electric field intensity is given by E = -Grad(V)- dA/dt, where V is the electric potential and A is the magnetic vector potential. When V is zero, then E = -dA/dt.
d
See lessExplanation: The electric field intensity is given by E = -Grad(V)- dA/dt, where V is the electric potential and A is the magnetic vector potential. When V is zero, then E = -dA/dt.
Harmonic electromagnetic fields refer to fields varying sinusoidally with respect to time. State True/False.
a Explanation: Fields that varying sinusoidally with respect to time are called as harmonic fields. An example for harmonic fields is A sin wt
a
See lessExplanation: Fields that varying sinusoidally with respect to time are called as harmonic fields. An example for harmonic fields is A sin wt
The surface integral of which parameter is zero?
c Explanation: The divergence of the magnetic flux density is always zero. By Stokes theorem, the surface integral of B is same as the volume integral of the divergence of B. Thus the surface integral of B is also zero.
c
See lessExplanation: The divergence of the magnetic flux density is always zero. By Stokes
theorem, the surface integral of B is same as the volume integral of the divergence of B. Thus the surface integral of B is also zero.
The charge build up in a capacitor is due to
b Explanation: The capacitor consists of a dielectric placed between two conducting plates, subjected to a field. The current due to a dielectric is always due to the displacement current density.
b
See lessExplanation: The capacitor consists of a dielectric placed between two conducting
plates, subjected to a field. The current due to a dielectric is always due to the
displacement current density.