Two points A and B are maintained at a potential of 7 V and -4 V respectively. The work done in moving 50 electrons from A to B is _______.

(a)

8.80 x 10^-17 J

(b)

-8.80 x 10^-17 J

(c)

4.40 x 10^-17 J

(d)

5.80 x 10^-17 J

The time taken by a conductor to reach electrostatic equilibrium is in the order of

(a)

10^-18

(b)

10^-14s

(c)

10^-16 s

(d)

10^-20 s

The force between like charges is _________.

(a)

attraction

(b)

repulsion

(c)

no force

(d)

none

A carbon resistor of (47 ± 4.7 ) k Ω to be marked with rings of different colours for its identification. The colour code sequence will be ______.

(a)

Yellow – Green – Violet – Gold

(b)

Yellow – Violet – Orange – Silver

(c)

Violet – Yellow – Orange – Silver

(d)

Green – Orange – Violet - Gold

The equivalent resistance between A and B in the figure is

(a)

\(15\Omega \)

(b)

\(7.5\Omega \)

(c)

\(25\Omega \)

(d)

\(30\Omega \)

Kirchhoff's law is applicable only for__________

(a)

simple circuits

(b)

primary circuits

(c)

complicated circuits

(d)

secondary circuits

A wire of length l carrying a current I along the Y direction is kept in a magnetic field is given by \(\vec { B } =\frac { \beta }{ \sqrt { 3 } } =(\hat { i } +\hat { j } +\hat { k } )T.\) The magnitude of Lorentz force acting on the wire is _____.

(a)

\(\sqrt { \frac { 2 }{ { 3 } } } \beta Il\)

(b)

\(\sqrt { \frac { 1 }{ { 3 } } } \beta Il\)

(c)

\(\sqrt { 2 } \beta Il\)

(d)

\(\sqrt { \frac { 1 }{ 2 } } \beta Il\)

Two short bar magnets have magnetic moments 1.20 Am² and 1.00 Am² respectively. They are kept on a horizontal table parallel to each other with their north poles pointing towards south. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centres is (Horizontal components of Earth’s magnetic induction is 3.6 × 10^–5 Wb m^–2 )

(a)

3.60 × 10^-5 Wb m^-2

(b)

3.5 × 10^-5 Wb m^-2

(c)

2.56 × 10^-4 Wb m^-2

(d)

2.2 × 10^-4 Wb m^-2

If the temperature of hot junction is increased beyond inversion temperature the thermo emf ______________.

(a)

is constant

(b)

increases

(c)

decreases

(d)

becomes zero

The orbital magnetic moment of an electron in the second orbit (n = 2) is _______________.

(a)

18.54 x 10^-24 Am²

(b)

18.54 x 10^-34 Am²

(c)

19.44 x 10^-34 Am²

(d)

19.44 x 10^-24 Am²

The quantity that changes with time in an A.C current is ________________.

(a)

magnitude

(b)

direction

(c)

both magnitude and direction

(d)

none

During the propagation of electromagnetic waves in a medium __________________.

(a)

electric energy density is double of the magnetic energy density

(b)

electric energy density is half of the magnetic energy density

(c)

electric energy density is equal to the magnetic energy density

(d)

both electric and magnetic energy densities are zero

Carbon are produces ________ spectrum.

(a)

characteristic

(b)

line

(c)

band

(d)

continuous

When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as plane sheet of glass. This implies that the liquid must have refractive index, ______.

(a)

less than one

(b)

less than that of glass

(c)

greater than that of glass

(d)

equal to that of glass

An object is placed at 20 cm from a convex mirror of focal length 10 cm. The image formed by the mirror is _____________.

(a)

Real and 20 cm from the mirror

(b)

Virtual and at 20 cm from the mirror

(c)

Virtual and 20/3 cm from the mirror

(d)

Real and 20/3 cm from the mirror

Two photons each of energy 2.5 eV are simultaneously incident on the metal surface. If the work function of the metal is 4.5 eV then from the surface of the metal ______________.

(a)

one electron will be emitted

(b)

two electrons will be emitted

(c)

more than two electrons will be emitted

(d)

not a single electron will be emitted

Electron microscope works on the principle of ________________.

(a)

photoelectron effect

(b)

particle nature of electron

(c)

wave nature of moving electron

(d)

dual nature of matter

If the kinetic energy of photo electron is found to be 16 J, whose mass is m_e, the maximum velocity of that electron will be _____________.

(a)

4\(\sqrt { \frac { 2 }{ { m }_{ e } } } \)

(b)

\(\sqrt { 4{ m }_{ e } } \)

(c)

\(\sqrt { \frac { 4 }{ { 2 }m_{ e } } } \)

(d)

\(\sqrt { \frac { 1 }{ { m }_{ e } } } \)

In an electron microscope, the electron beam is associated through a large potential difference in a device called _______

(a)

accelerator

(b)

electron gun

(c)

CRO

(d)

vibrator

The momentum for a wavelength of 0.01 Å is _________

(a)

6.626 x 10^-22 kgm/s

(b)

5 x 10^-24 kgm/s

(c)

6.5 x 10^-23 kgm/s

(d)

7.2 x 10^-34kgm/s

In J.J. Thomson e/m experiment, electrons are accelerated through 2.6 kV enter the region of crossed electric field and magnetic field of strength 3.0 x 10⁴ Vm^-1 and 1.0 x 10^-3 T, respectively, and pass through it and undeflected, then the specific charge is _____.

(a)

1.6 × 10¹⁰ C kg^–1

(b)

1.7 × 10¹¹ Ckg^–1

(c)

1.5 × 10¹¹ Ckg^–1

(d)

1.8 × 10¹¹ Ckg^–1

For hydrogen atom, the energy of the n^th orbit is given by, En = __________________.

(a)

\(\frac { 13.6 }{ { n }^{ 2 } } eV\)

(b)

0.53 n² eV

(c)

\(\frac { -13.6 }{ { n }^{ 2 } } eV\)

(d)

3 n² eV

If the distance between the conduction band and valence band is leV, then this combination is _______________.

(a)

semiconductor

(b)

metal

(c)

insulator

(d)

conductor

The output transducer of the communication system converts the radio signal into ________.

(a)

Sound

(b)

Mechanical energy

(c)

Kinetic energy

(d)

None of the above

Audio signal cannot be transmitted because _______________.

(a)

the signal has more noise

(b)

the signal cannot be amplitude for distance communication

(c)

the transmitting antenna length is very small to design

(d)

the transmitting antenna length is very large and impracticable