Free Printable EMF

1.

Consider a position vector of a point P is $P=a_x+2a_y+2a_z$ in a space having (0,0,0) as reference, what is the position vector of the same point if reference is shifted to Q(1,1,1)?

a)

$a_y+a_z$

b)

$-a_y-a_z$

c)

$2a_y+2a_z$

d)

$a_x+2a_y+2a_z$

2.

Determine the electrostatic force acting on an electron moving due to a net force of $(10a_x+20a_y)×10^{-30}$ in a space with gravitation:

a)

$(10a_x+10.9a_y)×10^{-30}$

b)

$(10a_x-10.9a_y)×10^{-30}$

c)

$(-10a_x-10.9a_y)×10^{-30}$

d)

None of the above

3.

Work done in moving an electron for a distance of 10cm along positive and negative x-directions in an electric field of $10a_xV/m$

a)

$-1.6×10^{-19}J\ and\ 1.6×10^{-19}J$

b)

$1.6×10^{-19}J\ and\ -1.6×10^{-19}J$

c)

$-1.6×10^{-19}J\ and\ -1.6×10^{-19}J$

d)

$1.6×10^{-19}J\ and\ 1.6×10^{-19}J$

4.

$If\ A=a_x+2a_y,\ B=2a_y$ and C forms a right-handed system, determine the unit vector along C

a)

$2a_x-a_y$

b)

$a_z$

c)

$-a_z$

d)

$-2a_x-a_y$

5.

Electromagnetic field theory deals directly with

a)

Electric field theory E

b)

Magnetic field theory H

c)

Both a) and b)

d)

Voltage V and Current I vectors

6.

Which of the following is a vector quantity?

a)

Mass

b)

Charge

c)

Potential

d)

Electric Field

7.

Use spherical coordinate system to find the area of the strip $α≤θ≤β$ on the spherical shell of radius ‘a’

a)

$2-a(\cosα-\cosβ)$

b)

$2-a^2(\cosα-\cosβ)$

c)

1

d)

0

8.

Field in the region describes the variation of a quantity in the region as a

a)

Mathematical function

b)

Graphical Sketch

c)

Both a and b

d)

None of these

9.

Surfaces $ρ=2\ \&\ z=2$ intersect in cylindrical coordinates in

a)

An infinite plane

b)

A semi-infinite plane

c)

A cylinder

d)

A circle

10.

Space variables involved in electromagnetic field theory are

a)

1

b)

2

c)

3

d)

4

11.

The use of vector analysis in electromagnetic field theory

a)

Saves time & provides economy of thought

b)

Gives a clear understanding of physics laws

c)

Mathematical analysis becomes easier

d)

All of these

12.

A point is represented in Cartesian coordinate as P (2, 6, 3), the radial component ρ in cylindrical coordinate will be

a)

Less than r in spherical coordinates

b)

greater than r in spherical coordinates

c)

equal to r in spherical coordinates

d)

unrelated to r in spherical coordinates

13.

A point is represented in Cartesian coordinate as P (-4, 8, 2), the azimuthal component φ in cylindrical coordinates will be

a)

Less than φ in spherical coordinates

b)

Greater than φ in spherical coordinates

c)

Equal to φ in spherical coordinates

d)

Unrelated to azimuthal component φ in spherical coordinates

14.

A field F is said to be solenoidal if

a)

∇ × F = 0

b)

∇ . F = 0

c)

∇ . ∇F = 0

d)

∫F . dl = 0

15.

∫∫(∇ × Pds where P is a vector, is equal to

a)

∫P . dl

b)

∫∇ × ∇ × P . dl

c)

∫∇ × P . dl

d)

∫∫∫∇ . Pdv

16.

If the divergence of a vector G is zero then

a)

The vector G can be expressed as the gradient of a scalar φ

b)

G can be expressed as CURL of a vector F

c)

∫G . dl = 0

d)

None of the above

17.

B = ∇ × A because

a)

Div B = 0

b)

∇ × B = 0

c)

∇ × ∇ × B = 0

d)

none of these

18.

A field A = 3x²yza_x + 3x²za_y + (x²y − 2z)a_zcan be termed as

a)

Harmonic

b)

Divergence less

c)

Solenoidal

d)

Rotational

19.

If $r⃗=x(a_x)⃗+y(a_y)⃗+z(a_z)⃗$ is the position vector of the point (x,y,z) & r = magnitude of r . What is the value of ∇r

a)

$r⃗/r$

b)

$r/r⃗$

c)

$rr⃗$

d)

0

20.

For a conservative field A, which one of the following is not true:

a)

Curl of A is zero

b)

Potential difference between any two arbitrary points is zero

c)

It is gradient of a scalar potential

d)

The work done in a closed path inside the field is zero

21.

The electric charges:

1. Are conserved

2. Are quantised

3. Exists in pair

4. Have a circular field around it

In the above statements, the following are true

a)

1 only

b)

1,2

c)

1,4

d)

1,2,3

22.

An electric potential field is produced in air by point charges 1μC and 4μC located at (-2, 1, 5) and (1, 3,-1) respectively. The energy stored in the field is:

a)

2.57mJ

b)

5.14 mJ

c)

10.28 mJ

d)

12.50mJ

23.

The electric field intensity E at 'P' due to an infinite line charge kept along one axis of the coordinate system is:

a)

Inversely proportional to the distance between them

b)

Inversely proportional to the square root of the distance

c)

Independent of the distance

d)

None of these

24.

Two-point charges + 8q and − 2q are located at x = 0 and x = L respectively. The location of a point on the x axis at which the net electric field due to these two-point charges is zero is

a)

L / 4

b)

2L

c)

4L

d)

8L

25.

Two small diameter dielectric balls of mass 5 milligram each can slide freely on a vertical non conducting thread. Each ball carries a negative charge of 2 μC. If the lower ball is restrained from moving, then the separation between the two will be:

a)

8570 mm

b)

857 mm

c)

85.7 mm

d)

8.57 mm

26.

Which statement does not say that electrostatic field is conservative?

a)

If the curl of E is identically zero

b)

The potential difference between two points is zero

c)

It is gradient of a scalar potential

d)

The work done in a closed path inside the field is zero

27.

A potential field is given by $V=3x^2y−yz$ The electric field at P (2, -1, 4) shall be:

a)

$12a_x−8a_yV/m$

b)

$12a_x−a_zV/m$

c)

$12a_x+8a_y+a_zV/m$

d)

$12a_x-8a_y-a_zV/m$

28.

The force between two point charges of 1nC each with a 1mm separation in air is:

a)

9 × 10−3 N

b)

9 × 10−6 N

c)

19 × 10−9 N

d)

9 × 10−12 N

29.

A hollow sphere of charge does not produce an electric field at any:

a)

Surface point

b)

Outer point

c)

Interior point

d)

None of these

30.

Gauss's law relates the electric field intensity E with the volume charge density ρ at a point as:

a)

∇ × E = ε₀ρ

b)

∇ . E = ε₀ρ

c)

∇ . E = ρ/ε

d)

∇ × E = ρ/ε

31.

A positive charge of Q coulombs is located at a point A (0, 0, 3) and a negative charge of magnitude Q coulombs is located at a point B (0, 0,-3). The electric field intensity at a point C (4, 0, 0) is in the:

a)

Negative x- direction

b)

Negative z- direction

c)

Positive x- direction

d)

Positive z- direction

32.

Which one of the following is a ceramic insulator?

a)

Mica

b)

Porcelain

c)

Liquid crystal

d)

Synthetic fiber

33.

In dielectric measurement, the dielectric loss is proportional to:

a)

F

b)

V

c)

I

d)

V²

34.

A medium is said to be isotropic when:

a)

ε is zero

b)

ε is a scalar constant

c)

ε is infinite

d)

All of the these

35.

Polarization is a measure of:

a)

Dielectric constant per unit volume

b)

Voltage gradient to produce electrical breakdown

c)

Product of charge and distance

d)

Excess charge density

36.

Which one of the following statements is incorrect?

a)

The conductivity of conductor & insulators vary with temperature & frequency

b)

A conductor is an equipotential body & E is always tangential to the conductor

c)

Non polar molecules have no permanent dipoles

d)

In all linear dielectric, P varies linearly with E

37.

A parallel plate capacitor of 5 pF capacitance has a charge of 0.1 μC on its plates. What is the energy stored in the capacitor?

a)

1 m Joules

b)

1 μ Joules

c)

1 n Joules

d)

1 p Joules

38.

The radius of earth is 6400 Km. Its capacitance is:

a)

6400 F

b)

711 μF

c)

711 pF

d)

6400 × 10⁹ F

39.

In a charge-free space, Poisson's equation results in which one of the following?

a)

Continuity equation

b)

Maxwell's equation

c)

Laplace's equation

d)

none of these

40.

A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is:

a)

Equal to that due to gravity

b)

Less than that due to gravity

c)

More than that due to gravity

d)

Depends on the diameter of the ring and the length of the magnet

41.

Significance of Gauss's law for magnetostatics:

a)

a) Non existence of monopole

b)

b) Existence of source & sinks

c)

c) Both a) & b)

d)

d) None of these

42.

Which of these statements is not characteristic of a static magnetic field?

a)

It is conservative

b)

It is solenoidal

c)

It has no sink or sources

d)

Magnetic flux lines are always closed

43.

A moving electric charge produces:

a)

Both electric and magnetic fields

b)

Electric field only

c)

Magnetic field only

d)

Neither of these two fields

44.

A length of a wire carries a steady current. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is:

a)

One fourth of its first value

b)

Unaltered

c)

Four times as before

d)

Half of its first value

45.

It is difficult to magnetize stainless steel because:

a)

High permeability

b)

low permeability

c)

high specific gravity

d)

corrodes easily

46.

The displacement current flows

a)

a) In a conductor

b)

b) In dielectric

c)

c) both (a) & (b)

d)

d) none of these

47.

Transformer e.m.f. is also called as

a)

a) Static e.m.f

b)

b) dynamic e.m.f.

c)

c) Both (a) & (b)

d)

d) none of these

48.

In a dielectric, the displacement current is ______ the conduction current in the wire connecting it to the supply

a)

greater than

b)

just equal to

c)

just less than

d)

none of these

49.

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

50.

An e.m.f. produced field Ef due to change in magnetic flux through the coil is

a)

Conservative

b)

non conservative

c)

curl-free

d)

none of these

51.

The magnetic vector potential A does not obey the equation

a)

B = ∇ × A

b)

H =-∇A

c)

∇²A =- μ₀ j

d)

none of them

52.

Two conducting thin coils X and Y (identical except for a thin cut in coil Y) are placed in a uniform magnetic field which is decreasing at a constant rate. If the plane of the coils is perpendicular to the field lines, which of the following statement is correct? As a result, emf is induced in

a)

Both the coils

b)

Coil Y only

c)

Coil X only

d)

None of the coils

53.

For static electric and magnetic fields in an inhomogeneous 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 = J

c)

∇ . E = 0 ∇ × B = 0

d)

∇ × E = 0 ∇ . B = 0

54.

Poynting vector is based on

a)

Seebeck effect

b)

Ferranti effect

c)

Induction effect

d)

Hall effect

55.

The skin depth of a non-magnetic conducting material at 100 MHz is 0.15 mm. The distance which a plane wave of frequency 10 GHz travels in this material before its amplitude reduces by a factor of e−1 is

a)

0.0015 mm

b)

0.015 mm

c)

0.15 mm

d)

1.5 mm

56.

A uniform plane wave travelling in air incident on the plane boundary between air & another dielectric medium with ∈r = 4.0. The reflection coefficient for the normal incidence is

a)

Zero

b)

0.5 ∠180°

c)

0.333 ∠0°

d)

0.333 ∠180°

57.

When a plane wave travelling in free space is incident normally on a medium having ε_r = 4.0, the fraction of power transmitted into the medium is given by

a)

8/9

b)

½

c)

1/3

d)

5/6

58.

A plane wave having x directed electric field propagating in free space along the z- direction is incident on an infinite electrically conducting (perfect conductor) sheet at z = 0 plane. Which one of the following is correct?

a)

The sheet will absorb the wave

b)

There will be x-directed surface electric current on the sheet

c)

There will be y-directed surface electric current on the sheet

d)

There will be magnetic current in the sheet

59.

Consider the following statements with reference to Brewster angle:

1. For oblique incidence at a boundary, there is no reflected wave vertically polarized.

2. Brewster angle can occur only at the boundary of a perfect conductor.

3. For a horizontally polarized wave, there is no brewster angle

4. When the incident wave is not fully vertically polarized, there will be a reflected component which is horizontally polarized

Which of these statements are correct?

a)

1, 2 and 3

b)

2, 3 and 4

c)

3, 4 and 1

d)

4, 1 and 2

60.

If the electric field intensity associated with a uniform electromagnetic plane wave travelling in a perfect dielectric medium is given by E (z, t) = 10 cos (2 × 10 ⁷ t-0.1z) volt/m then the velocity of the travelling wave is

a)

3 × 10⁸ m/s

b)

2 ×10 ⁸ m/s

c)

6.28 × 10⁷ m/s

d)

2 × 10⁷ m/s

EMF - A2

Total questions: 60

Worksheet time: 51mins

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