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Questions:

Multiple Choice Question

50 x 1 = 50

Fraunhofer lines are an example of ______ spectrum.

(a)

line emission

(b)

line absorption

(c)

band emission

(d)

band absorption

one amu (u) is equal to _____________.

(a)

931eV

(b)

mass of carbon atom

(c)

1 .66 x10^-27 kg

(d)

mass of oxygen atom

The refractive index of the material of a prism is $\sqrt{2}$ and its refracting angle is 30^o. One of the refracting surfaces of the prism is made a mirror inwards. A beam of mono chromatic light entering the prism from the other face will retrace its path after reflection from the mirror surface of its angle of incidence on the prism is __________.

(a)

45^o

(b)

60^o

(c)

(d)

30^o

An alpha particle moves with a velocity of 5 x 10⁵ m/s at an angle of 30^o with respect to a magnetic field of induction 10^-4 T. Then the force acting on the particle is _____________.

(a)

16 x 10^-18 N

(b)

4 x 10^-18 N

(c)

8 x 10^-18 N

(d)

2 x 10^-18 N

If the resistance of a coil is $2 \Omega$ at 0^oC and $\alpha=0.004 /{ }^{\circ} \mathrm{C}$ then its resistance at 100^oC is ______________.

(a)

$1.4 \Omega$

(b)

$5.6 \Omega$

(c)

$2.8 \Omega$

(d)

$4 \Omega$

Find the kinetic energy if hv = 2.1 eV and work function is given as 5 x 10^-19J.

(a)

0.288 eV

(b)

0.288 J

(c)

1.025 eV

(d)

5 eV

Stopping potential of emitted photo electrons is given by (where ф = hv₀) _____________.

(a)

$\frac { hv-{ \phi }_{ 0 } }{ e } $

(b)

hv-ф

(c)

$\frac { hv }{ e } $

(d)

$\frac { hv+{ \phi }_{ 0 } }{ e } $

For a transistor, in a common base configuration the alternating current gain is given by ______________.

(a)

${ \left[ \frac { \triangle { I }_{ C } }{ \triangle { I }_{ B } } \right] }_{ { V }_{ c }=constant }$

(b)

${ \left[ \frac { \triangle { I }_{ B } }{ \triangle { I }_{ C } } \right] }_{ { V }_{ c }=constant }$

(c)

${ \left[ \frac { \triangle { I }_{ C } }{ \triangle { I }_{ E } } \right] }_{ { V }_{ c }=constant }$

(d)

${ \left[ \frac { \triangle { I }_{ E } }{ \triangle { I }_{ C } } \right] }_{ { V }_{ c }=constant }$

An alpha nucleus of energy 1/2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of the closest approach for the alpha nucleus will be proportional to ____________.

(a)

v²

(b)

$\frac{1}{m}$

(c)

$\frac{1}{v^$}$

(d)

$\frac{1}{Ze}$

10.

The particle which gives mass to protons and neutrons are _____.

(a)

Higgs particle

(b)

Einstein particle

(c)

Nanoparticle

(d)

Bulk particle

11.

“Sky wax” is an application of nano product in the field of _____.

(a)

Medicine

(b)

Textile

(c)

Sports

(d)

Automotive industry

12.

Which one of the following is the natural nanomaterial.

(a)

Peacock feather

(b)

Peacock beak

(c)

Grain of sand

(d)

Skin of the Whale

13.

The given electrical network is equivalent to ______.

(a)

AND gate

(b)

OR gate

(c)

NOR gate

(d)

NOT gate

14.

The light emitted in an LED is due to ______.

(a)

Recombination of charge carriers

(b)

Reflection of light due to lens action

(c)

Amplification of light falling at the junction

(d)

Large current capacity

15.

If a positive half-wave rectified voltage is fed to a load resistor, for which part of a cycle there will be current flow through the load?

(a)

0⁰–90⁰

(b)

90⁰–180⁰

(c)

0⁰–180⁰

(d)

0⁰–360⁰

16.

If a small amount of antimony (Sb) is added to germanium crystal,______.

(a)

it becomes a p-type semiconductor

(b)

the antimony becomes an acceptor atom

(c)

there will be more free electrons than hole in the semiconductor

(d)

its resistance is increased

17.

The half-life period of a radioactive element A is same as the mean life time of another radioactive element B. Initially both have the same number of atoms. Then _____.

(a)

A and B have the same decay rate initially

(b)

A and B decay at the same rate always

(c)

B will decay at faster rate than A

(d)

A will decay at faster rate than B

18.

If the nuclear radius of ²⁷Al is 3.6 fermi, the approximate nuclear radius of ⁶⁴Cu, in femi is _____.

(a)

2:4

(b)

1.2

(c)

4.8

(d)

3.6

19.

Atomic number of H-like atom with ionization potential 122.4 V for n = 1 is _____.

(a)

(b)

(c)

(d)

20.

The work functions for metals A, B and C are 1.92 eV, 2.0 eV and 5.0 eV respectively. The metal/metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are _____.

(a)

A only

(b)

both A and B

(c)

all these metals

(d)

none

21.

If the mean wavelength of light from sun is taken as 550 nm and its mean power as 3.8 x 10²⁶W, then the number of photons emitted per second from the sun is of the order of _____.

(a)

10⁴⁵

(b)

10⁴²

(c)

10⁵⁴

(d)

10⁵¹

22.

A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ /2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the material is _____.

(a)

$\frac{hc}{\lambda}$

(b)

$\frac{2hc}{\lambda}$

(c)

$\frac{hc}{3\lambda}$

(d)

$\frac{hc}{2\lambda}$

23.

In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de Broglie wavelength associated with the electrons would _____.

(a)

increase by 2 times

(b)

decrease by 2 times

(c)

decrease by 4 times

(d)

increase by 4 times

24.

One of the of Young’s double slits is covered with a glass plate as shown in figure. The position of central maximum will,_____.

(a)

get shifted downwards

(b)

get shifted upwards

(c)

will remain the same

(d)

data insufficient to conclude

25.

Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are _____.

(a)

5I and I

(b)

5I and 3I

(c)

9I and I

(d)

9I and 3I

26.

Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm approximately. The maximum distance at which these dots can be resolved by the eye is_____. [take wavelength of light, λ = 500 nm]

(a)

1 m

(b)

5 m

(c)

3 m

(d)

6 m

27.

A ray of light travelling in a transparent medium of refractive index n falls, on a surface separating the medium from air at an angle of incidents of 45^o . The ray can undergo total internal reflection for the following n, ______.

(a)

n = 1.25

(b)

n = 1.33

(c)

n = 1.4

(d)

n = 1.5

28.

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

29.

If the velocity and wavelength of light in air is V_a and λ_a and that in water is V_w and λ_w, then the refractive index of water is______.

(a)

$\frac{V_W}{V_a}$

(b)

$\frac{V_a}{V_W}$

(c)

$\frac{\lambda_W}{\lambda_a}$

(d)

$\frac{{V_a}\lambda_a}{{V_W}\lambda_W}$

30.

An object is placed in front of a convex mirror of focal length off and the maximum and minimum distance of an object from the mirror such that the image formed is real and magnified.

(a)

2f and c

(b)

c and $\infty$

(c)

f and O

(d)

None of these

31.

Speed of electromagnetic waves through vacuum is equal to ______________.

(a)

$\sqrt { { \mu }_{ 0 }{ \varepsilon }_{ 0 } } $

(b)

$\frac { 1 }{ \sqrt { { \mu }_{ 0 }{ \varepsilon }_{ 0 } } } $

(c)

$\\ \frac { \sqrt { { \mu }_{ 0 } } }{ { \varepsilon }_{ 0 } } $

(d)

$\sqrt { \frac { { \varepsilon }_{ 0 } }{ { \mu }_{ 0 } } } $

32.

The average time between two successive collision of an electron is 3.64 x 10^-8 s. Its mobility is __________.

(a)

6.4 x 10³ m² V^-I S^-I

(b)

640 m² m V S^-1

(c)

6.4 x 10³ m V^-1S^-1

(d)

6.4 x 10³m² V S^-1

33.

Two charges are kept at a distance in air what should be the relative permittivity of the medium in which the two charges should be kept at the same distance so that they experience half of the force which they experienced in air?

(a)

$\frac{1}{2}$

(b)

$\frac{1}{0.2}$

(c)

(d)

0.2

34.

The value of constant 'K' in coulomb law is _____________.

(a)

0.9 x 10⁹ Nm² C²

(b)

9 x 10^-9 Nm²C²

(c)

9 x 10⁹ Nm^-2 C^-2

(d)

9 x 10⁹ Nm² C^-2

35.

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

36.

Three wires of equal lengths are bent in the form of loops. One of the loops is circle, another is a semi-circle and the third one is a square. They are placed in a uniform magnetic field and same electric current is passed through them. Which of the following loop configuration will experience greater torque?

(a)

Circle

(b)

Semi-circle

(c)

Square

(d)

All of them

37.

A particle having mass m and charge q accelerated through a potential difference V. Find the force experienced when it is kept under perpendicular magnetic field $\vec { B } $.

(a)

$\sqrt { \frac { 2{ q }^{ 3 }BV }{ m } } $

(b)

$\sqrt { \frac { { q }^{ 3 }{ B }^{ 2 }V }{ 2m } } $

(c)

$\sqrt { \frac { 2{ q }^{ 3 }{ B }^{ 2 }V }{ m } } $

(d)

$\sqrt { \frac { { 2q }^{ 3 }BV }{ { m }^{ 3 } } } $

38.

An electron moves in a straight line inside a charged parallel plate capacitor of uniform charge density σ. The time taken by the electron to cross the parallel plate capacitor undeflected when the plates of the capacitor are kept under constant magnetic field of induction $(\vec{B})$ is

(a)

${ \varepsilon }_{ ° }\frac { elB }{ \sigma } $

(b)

${ \varepsilon }_{ ° }\frac { lB }{ \sigma {l} } $

(c)

${ \varepsilon }_{ ° }\frac { lB }{ {e}\sigma } $

(d)

${ \varepsilon }_{ ° }\frac { lB }{ \sigma } $

39.

In a series resonant RLC circuit, the voltage across 100 Ω resistor is 40 V. The resonant frequency ω is 250 rad/s. If the value of C is 4 µF, then the voltage across L is

(a)

600 V

(b)

4000 V

(c)

400 V

(d)

1 V

40.

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is

(a)

2 A

(b)

18 A

(c)

12 A

(d)

1 A

41.

The flux linked with a coil at any instant t is given by $\Phi$_B = 10t²− 50t + 250. The induced emf at t = 3s is

(a)

−190 V

(b)

−10 V

(c)

10 V

(d)

190 V

42.

Which one of them is used to produce a propagating electromagnetic wave?

(a)

an accelerating charge

(b)

a charge moving at constant velocity

(c)

a stationary charge

(d)

an uncharged particle

43.

Which of the following electromagnetic radiations is used for viewing objects through fog

(a)

microwave

(b)

gamma rays

(c)

X- rays

(d)

infrared

44.

Two metallic spheres of radii 1 cm and 3 cm are given charges of -1 $\times$ 10^-2 C and 5 $\times$ 10^-2 C respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is

(a)

3 $\times$ 10^-2 C

(b)

4 $\times$ 10^-2 C

(c)

1 $\times$ 10^-2 C

(d)

2 $\times$ 10^-2 C

45.

A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface. The correct plot for electrostatic potential due to this spherical shell is _____.

(a)

(b)

(c)

(d)

46.

What is the ratio of the charges $\left| \frac { { q }_{ 1 } }{ { q }_{ 2 } } \right| $ for the following electric field line pattern?

(a)

$\frac { 1 }{ 5 } $

(b)

$\frac { 25 }{ 11 } $

(c)

(d)

$\frac { 11 }{ 25 } $

47.

A piece of copper and another of germanium are cooled from room temperature to 80 K. The resistance of ______.

(a)

each of them increases

(b)

each of them decreases

(c)

copper increases and germanium decreases

(d)

copper decreases and germanium increases

48.

There is a current of 1.0 A in the circuit shown below. What is the resistance of P ?

(a)

1.5 Ω

(b)

2.5 Ω

(c)

3.5 Ω

(d)

4.5 Ω

49.

In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be ______.

(a)

(b)

(c)

$\frac{R}{4}$

(d)

$\frac{R}{2}$

50.

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

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Answers Key:

Multiple Choice Question

50 x 1 = 50

(b)
line absorption

sin i = n x sin r
$=\sqrt{2} \times \sin 30$
$=\sqrt{2} \times \frac{1}{2}=\frac{1}{\sqrt{2}}$
$\therefore i=45^{\circ}$

F = Bqv sin θ
= B(2e) v sin 30
= 10^-4 x 2 x1.6 x 10^-19 x 5 x 10⁵ x 0.5
= 8 x10^-18 N

(a)
$\frac { hv-{ \phi }_{ 0 } }{ e } $

(b)
$\frac{1}{m}$

10.

Proton and neutron are made up of quarks. Later, it was found that Higg's particles or God particles give mass to the particles like protons, neutrons etc.

11.

12.

Wings of a morpho butterfly, peacock feathers, lotus leaf surface and sources of parrot fish's bite are some of the natural nano particles.

13.

$Y_1=\overline{A+B}, y_2=\overline{A+B}=A+B, y=\overline{A+B}$

14.

(a)
Recombination of charge carriers

15.

16.

17.

T_A1/2 = ፒ_B
$\frac{0.6931}{\lambda_{\mathrm{A}}}=\frac{1}{\lambda_{\mathrm{B}}} $
$\lambda_{\mathrm{B}}=\frac{\lambda_{\mathrm{A}}}{0.6931}=1.44 \lambda_{\mathrm{A}}$
Hence, B will decay at faster rate than A

18.

$r \propto A^{\frac{1}{3}} $
$\frac{r_{\mathrm{Cu}}}{\mathrm{r}_{\mathrm{Al}}}=\frac{\mathrm{A}_{\mathrm{Cu}}^\frac{1}{3}}{\mathrm{~A}_{\mathrm{Al}}^{\frac{1}{3}}}=\frac{4}{3} $
$\mathrm{r}_{\mathrm{Cu}}=\frac{4}{3} \times 3.6 \mathrm{~F}=4.8 \mathrm{~F}$

19.

$V_{ionisation}=\frac{13.6}{n^2}Z^2 volt$
$Z=\sqrt\frac{V\times n^2}{13.6}=\sqrt\frac{122.4 \times I^2}{13.6}=\sqrt{9}=3$

20.

$E=\frac{12400 \stackrel{o}A}{4100 \stackrel{o}A}=3.02 eV$

21.

$\mathrm{P} =\frac{\mathrm{n}}{\mathrm{t}} \frac{\mathrm{hc}}{\lambda} $
$\frac{\mathrm{n}}{\mathrm{t}} =\frac{\mathrm{P} \lambda}{\mathrm{hc}} $
$\frac{\mathrm{n}}{\mathrm{t}} =\frac{3.8 \times 10^{26} \times 550 \times 10^{-9}}{6.6 \times 10^{-3} \times 3 \times 10^8}=1 \times 10^{-15}$

22.

$\frac{\mathrm{hc}}{\lambda} =\phi+\mathrm{K} . \mathrm{E} .....(1) $
$\frac{2 \mathrm{hc}}{\lambda} =\phi+3 \mathrm{~K} . \mathrm{E}......(2)$
multiply eqn. (1) by 3, we get
$\frac{3 \mathrm{hc}}{\lambda} =3\phi+3 \mathrm{~K} . \mathrm{E} .....(3)$
Subtract eqn. (2) from (3), we get
$\frac{\mathrm{hc}}{\lambda} =2\phi $
$\phi=\frac{ \mathrm{hc}}{2\lambda} $

23.

$\lambda\propto \frac{1}{\sqrt{V}}$
$\frac{\lambda_1}{\lambda_2}=\frac{\sqrt{224\times10^3}}{\sqrt{14\times 10^3}}$
$=\sqrt{16}=4$
$\lambda_{\mathrm{2}}= \frac{\lambda_1}{4}$

24.

(b)
get shifted upwards

25.

I = l₁ + l₂ + 2$\sqrt{I_1I_2}$cos θ
If cos θ = cos 0 = l, I is max
= I+ 4I + 2$\sqrt{41^2}$ cos 0
= 5I + 4I = 91
If cos π = -1, I is min
I_min = I + 4I + 2$\sqrt{41^2}$ cos π
= 5I + 4I(-1)
= 5I + 4I = I
(I_max, I_min)= (9I, I)

26.

λ = 500 nm = 500 x 10^-9 m
x = 3 mm = 3 x 10^-3 m
a = 1 mm = 1 x 10^-3 m
$d=\frac{xa}{1.22 \lambda}$
$d=\frac{3 \times1\times10^{-6}}{1.22 \times500\times10^{-9}}$
$=\frac{3 \times1\times10^{-6}}{6.10 \times 10^{-7}}$
$d=\frac{30}{6.1}=5 m$

27.

For total internal reflection,
sin i > sin c
$n=\frac{1}{sin \ c}$
$sin \ c=\frac{1}{n}$
$sin \ i>\frac{1}{n}$
$n>\frac{1}{sin \ i}$
n >$\sqrt{2}$
n >1.414 = 1.5

28.

$\frac{I}{f}=\left(\frac{\mu_{\mathrm{L}}}{\mu_L}-1\right)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)$
When the biconvex lens of glass dipped in liquid, it acts as a plane sheet of glass.
$\therefore \mathrm{f}=\infty, \frac{1}{\mathrm{f}}=0 \quad \frac{\mu_g}{\mu_{\mathrm{L}}}-1=0 ; \frac{\mu_{\mathrm{s}}}{\mu_{\mathrm{L}}}=1, \mu_{\mathrm{s}}=\mu_{\mathrm{L}}$

29.

Refractive index of water $=\frac{Velocity \ of \ light \ in \ air(V_s)}{Velocity \ of \ light \ in \ water(V_w)}$

30.

Convex Mirror is diverging in nature and for all positions of objects, convex mirror forms virtual and erect image.

31.

(b)
$\frac { 1 }{ \sqrt { { \mu }_{ 0 }{ \varepsilon }_{ 0 } } } $

32.

(a)
6.4 x 10³ m² V^-I S^-I

33.

(b)
$\frac{1}{0.2}$

34.

(d)
9 x 10⁹ Nm² C^-2

35.

36.

(a)
Circle

37.

Lorentz force F = Bqv
Energy w = qV
Energy is equal to kinetic energy,
$qV=\frac{1}{2}mv^2$
$v=\sqrt { \frac {2qV }{ m } } $
$\therefore Lorentz \ force \ F= Bq\times \sqrt \frac{2qV}{m}=\sqrt { \frac { 2{ B }^{ 2 }{ q }^{ 3 }V }{ m } } $

38.

Electric field between the plates $= \frac{σ}{ε_0}$
Electric force on an electron $= e\frac{σ}{ε_0}$
Magnetic force on an electron, F = BIl
But, $I= \frac{e}{t}$
∵Electron moves in a straight line. So,
E_F= M_F
$e\frac{σ}{ε_0}=B(\frac{e}{t})l$
$\therefore t = ε_0\frac{lB}{σ}$

39.

$\omega=250 \mathrm{rad} / \mathrm{s}, C=4 \times 10^{-} \mathrm{F} $
$R=100 \Omega, \quad \mathrm{V}_{\mathrm{R}}=40 \mathrm{~V} $
$\therefore I_{\mathrm{R}}=\frac{V_R}{100}=\frac{40}{100}=0.4 \mathrm{~A} $
$\omega=\frac{1}{\sqrt{L C}} $
$\omega^2=\frac{1}{L C} $
$(250)^2=\frac{1}{L \times 4 \times 10^{-6}} $
$L=\frac{1}{4 \times(250)^2 \times 10^{-6}} $
$=\frac{1}{4 \times 250 \times 250 \times 10^{-6}} $
$=\frac{1}{1000 \times 10^{-6} \times 250} $
$=\frac{10^3}{250}=\frac{1000}{250}=4 \mathrm{H}$
Voltage acnoss L, V_t= IX_L
V_L= l x L x ω
= 0.4 x 4 x 250
0.4 x 1000 = 400 V

40.

(a)
2 A

41.

$\phi_B =10 t^2-50 t+250 $
$e =\frac{-d \phi_B}{d t} $
$=\frac{-d}{d t}\left(10 t^2-50 t+250\right) $
=-(20 t - 50)
=-20 t + 50
When, t = 3 s, e =-20(3) + 50 = -60 + 50
e = -10V

42.

(a)
an accelerating charge

43.

(d)
infrared

44.

Q = q₁ + q₂ = 4 x 10^-2C
$q_{2f}=Q[\frac{r_2}{r_1+r_2}]$
= 4 x 10^-2 $[\frac{3}{4}]$
q_2f= 3 x 10^-2 C

45.

46.

q ∝ Φ
∴ $\frac {q_1}{q_2} = \frac {Φ_1}{Φ_2}=\frac{11}{25}$

47.

Resistivity ∝ temperature for conductor. so, copper → decreases
Resistivity ∝$\frac{1}{\text {temperature for semiconductor}}$
so, germanium → increases.

48.

R_s = 3 + 2.5 + P = 5.5 + P
V = 9 V, I = 1.0 A
R_s = $\frac{V}{I}=\frac{9}{1}= 9 \Omega$
∴ 9 = 5.5 + P
∴ P = 9 - 5.5 = 3.5 Ω

49.

$\mathrm{V}_1 =220 \mathrm{~V}, \quad \mathrm{P}_1=60 \mathrm{~W} $
$\mathrm{~V}_{\mathrm{U}} =110 \mathrm{~V}, \mathrm{P}_{\mathrm{U}}=60 \mathrm{~W} $
$P =\frac{V^2}{R} \Rightarrow R=\frac{V^2}{P} $
$\therefore R_l =\frac{V_I^2}{P_l} \text { Similarly, } \quad \mathrm{R}_U=\frac{V_U^2}{P_U} $
$R_l =\frac{220 \times 220}{60} \quad \mathrm{R}_{\mathrm{U}}=\frac{110 \times 110}{60} $
$R_I =\frac{48400}{60} \quad R_U=\frac{12100}{60} $
$\frac{R_U}{R_l} =\frac{12100}{60} \times \frac{60}{48400}=\frac{1}{4} $
$R_U =\frac{R_l}{4}=\frac{R}{4}$

50.

Yellow - 4
Violet - 7
Orange - 10³
Silver - Tolerance - 10%