Free Printable EMF UT 2 (SECTION-I)

1.

Which of the following statements are incorrect?

a)

Displacement current exists inside perfect solid conductor

b)

Displacement current exists inside a perfect sheet of conductor

c)

Current density and current are directly proportional

d)

Current density and current are indirectly proportional

2.

Which of the following is not described in Faraday's experiment?

a)

Change in magnetic flux linkage

b)

Electromotive force

c)

Static Electric field

d)

Number of turns in a closed circuit

3.

The concept of displacement current was a major contribution attributed to

a)

Faraday

b)

Gauss

c)

Ampere

d)

Maxwell

4.

Which one of the following is correct?Which one of the following is correct?

a)

Pointing vector is a power density vector.

b)

Faraday discovered conduction current density

c)

Ampere discovered Electromagnetic induction

d)

Gauss law relates curl of magnetic field

5.

According to Amperes law

a)

Total electric flux is equal to electric charge

b)

Total magnetic flux is equal to electric charge

c)

Total magnetic flux is equal to total current

d)

Total electric flux is equal to total current

6.

In free space Electric field E is E= $20\cos⁡(10^{12}t-50x)(a_y)⃗V/m$ Its magnetic field is?

a)

$H⃗=10.62\cos⁡(10^{12}t-50x)(a_z)⃗A/m$

b)

$H⃗=1.77\cos⁡(10^{12}t-50x)(a_z)⃗A/m$

c)

$H⃗=3.54\cos⁡(10^{12}t-50x)(a_z)⃗A/m$

d)

$H⃗=21.2\cos⁡(10^{12}t-50x)(a_z)⃗A/m$

7.

A material has a conductivity of 0.01mho/m and a relative permittivity of 4. The frequency at which conduction current in the medium is equal to the displacement current is, (Gate 2001)

a)

400 MHz.

b)

90 MHz.

c)

45 MHz.

d)

900 MHz

8.

In an Electromagnetic wave the Electric field lies along X direction and the wave is propagating along Y direction, then the direction of Magnetic field is,

a)

Along positive Z direction

b)

Along negative X direction

c)

Along positive X direction

d)

Along negative Z direction

9.

Which of the following represents continuity of current?

a)

$∇.H⃗=0$

b)

$∇.J⃗=-(∂ρ_v)/∂t$

c)

$∇×E⃗=-(∂B⃗)/∂t$

d)

$∇×H⃗=I$

10.

Inconsistency in the Ampere's circuit law for time varying fields is eliminated by introducing.

a)

Conduction current density

b)

Transformer e.m.f.

c)

A combination of motional & transformer e.m.f.

d)

None of these

11.

A time varying field is applied to a circuit with a capacitor

a)

The current in the circuit consists of conduction current and displacement current

b)

The displacement current passes through the capacitor

c)

conduction current is equal to displacement current

d)

all of the above

12.

For static electric and magnetic fields in an in homogeneous source-free medium, which of the following represents the correct form of two of Maxwell's equations?

a)

∇ . E = 0, ∇ × B = J

b)

∇ × E = 0,∇ . B = 0

c)

∇ . E = 0, ∇ × B = J

d)

∇ . E = 0,∇ × B = 0

13.

The charge builds up in a capacitor is due to

a)

Conduction current density

b)

Displacement current density

c)

Convection current density

d)

Polarisation

14.

Find the curl of E when B is given as 15t.

a)

15

b)

-15

c)

7.5

d)

-7.5

15.

Find the electric field applied on a system with electrons having a velocity 5m/s subjected to a magnetic flux of 3.6 units.

a)

15

b)

18

c)

1.38

d)

0.72

16.

Calculate the emf when the flux is given by 3sint + 5cost

a)

3cos t – 5sin t

b)

-3cos t + 5sin t

c)

-3sin t – 5cos t

d)

3cos t + 5sin t

17.

Which one of the following laws will not contribute to the Maxwell’s equations?

a)

Gauss law

b)

Faraday law

c)

Ampere law

d)

Biot Savart’s law

18.

$Magneticfieldintensityis.\left(H⃗=3(a_x)⃗+7y(a_y)⃗+2x(a_z)⃗A/mH⃗a_y\right)$ A/m What is the current density A/m2?

a)

$-2(a_y)⃗$

b)

$-7(a_z)⃗$

c)

$3(a_x)⃗$

d)

$12(a_y)⃗$

19.

Divergence of curl of a vector H=x²ax+6y²ay+ z²az is

(a)

20.

If C is a closed curve enclosing a surface S, then the magnetic field intensity 𝐻, the current density 𝐽 and the electric flux density 𝐷 are related by

a)

$∫_sH.ds=∫_c(J+∂D/∂t).dl$

b)

$∫_sH.dl=∫_c(J+∂D/∂t).ds$

c)

$∫_cH.ds=∫_s(J+∂D/∂t).dl$

d)

$∫_cH.dl=∫_s(J+∂D/∂t).ds$

EMF UT 2 (SECTION-I)

Total questions: 20

Worksheet time: 24mins

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