12th Standard English Medium Physics Reduced syllabus One mark important Questions - 2021(Public Exam )

Download Tamil Nadu 12th Standard Physics question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.

Questions:

Multiple Choice Question

50 x 1 = 50

A rear mirror of a vehicle is cylindrical having a radius of curvature of 10 cm. The length of the arc of the curved surface is also 10 cm. If the eye of the driver is assumed to be at a large distance, from the mirror, then the field of view in radian is ____________.

(a)

0.5

(b)

(c)

(d)

Find the energy released when 5.5 g of matter is used.

(a)

1.6 x 10⁸ J

(b)

49.5 x 10¹⁵ J

(c)

49.5 x 10¹⁵ J

(d)

1.6 x 10¹⁹J

Best example for applications of nanotechnology is ______________.

(a)

Chemical industry

(b)

Engineering

(c)

medicine

(d)

all of these

Output characteristics of an NPN, transistor in CE mode is drawn between ___________

(a)

I_C and V_BE

(b)

I_E and V_CE

(c)

I_Band V_CE

(d)

I_C and V_CE

Input characteristics of an NPN transistor in (CE mode) is drawn between ________

(a)

I_B and V_BE

(b)

V_BEand V_CE

(c)

V_CC and V_EE

(d)

V_B and I_E

Acceptor of majority charge carriers in a transistor is ___________

(a)

emitter

(b)

base

(c)

collector

(d)

resistor.

Supplier of majority charge carriers in a transistor is ______

(a)

emitter

(b)

base

(c)

collector

(d)

resistor

The distance of a geostationary satellite's orbit from the Earth is about _______

(a)

366 km

(b)

108 km

(c)

36 x 10³km

(d)

30 m

________ wire is used between telephones and the central office

(a)

Flat

(b)

Multiconnector

(c)

Co-axial

(d)

Twisted pair

10.

The circuit in which an inductor and a capacitor are connected in parallel is called as a _________

(a)

tank

(b)

series

(c)

inductor

(d)

capacitor

11.

The speaker converts ________ energy into ______ energy.

(a)

electrical, sound

(b)

sound, electrical

(c)

light, sound

(d)

sound, mechanica

12.

The centre of frequency is extremely stable in ___________ modulated wave.

(a)

amplitude

(b)

frequency

(c)

phase

(d)

pulse-code

13.

Low efficiency and small operating range are features of _________ type of transmission.

(a)

(b)

(c)

PCM

(d)

14.

Long distance radio communication employs _______ wave propagation.

(a)

ground

(b)

sky

(c)

space

(d)

surface

15.

Broadcasting antennas are generally ______________.

(a)

unidirectional

(b)

vertical

(c)

horizontal

(d)

none

16.

In frequency modulation _____________.

(a)

the amplitude of modulated wave varies as frequency

(b)

the frequency of modulated wave varies as amplitute the frequency

(c)

the amplitude of modulated wave varies as amplitute of carrier wave

(d)

the frequency of modulated wave varies as frequency of modulating wave

17.

The input resistance is ________

(a)

1k Ω

(b)

10 Ω

(c)

10 k Ω

(d)

100 Ω

18.

The Ac current gain of a transistor is 100. If the base current changes by 100 μA. What is the charge in the collector current ______.

(a)

20 mA

(b)

30 mA

(c)

10 mA

(d)

10 μA

19.

The moderator used in nuclear reactor is ________________.

(a)

Cadmium

(b)

Boron oxide

(c)

Heavy water

(d)

Uranium

20.

Minimum size of a system in which at least 1 neutron is available for further fission is called __________

(a)

cut-off size

(b)

critical size

(c)

range of reactor

(d)

capability criteria

21.

In the nuclear reaction ₄Be⁹+ X ➝₆C¹²+ ₀n¹ X stands for ______________.

(a)

proton

(b)

α particle

(c)

electron

(d)

deutron

22.

In gamma ray emission from nucli _____________.

(a)

both the neutron number and the proton number change

(b)

there is no change in neutron number and the proton number change

(c)

only the neutron number changes

(d)

only the proton number changes

23.

When the electron jumps from any of the outer orbits to the first orbit, spectral lines are emitted in the ________ region.

(a)

visible

(b)

(c)

X-ray

(d)

24.

A spray of fine droplets of a highly viscous liquid could be, accomplished by a _________

(a)

filter

(b)

steve

(c)

atomizer

(d)

mixer

25.

J.J. Thomson discovered ________

(a)

protons

(b)

neutrons

(c)

electrons

(d)

quarks

26.

When an electric field is applied to an atom each of the spectral lines split into several lines. This effect is known as ________________.

(a)

Zeeman effect

(b)

Stark effect

(c)

Raman effect

(d)

Seebeck effect

27.

A beam of electron posses undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained, the electrons move ______________.

(a)

in a circular orbit

(b)

along a parabolic path

(c)

along a straight line

(d)

in an elliptical orbit

28.

Millikan's oil drop experiment established that is ____________.

(a)

electric charge depends on velocity

(b)

electric charge is quantised

(c)

electron has wave nature

(d)

electron has particle nature

29.

The method of making nanomaterial by assembling the atoms is called _____.

(a)

Top down approach

(b)

Bottom up approach

(c)

Cross down approach

(d)

Diagonal approach

30.

The blue print for making ultra durable synthetic material is mimicked from _____.

(a)

Lotus leaf

(b)

Morpho butterfly

(c)

Parrot fish

(d)

Peacock feather

31.

The variation of frequency of carrier wave with respect to the amplitude of the modulating signal is called ______.

(a)

Amplitude modulation

(b)

Frequency modulation

(c)

Phase modulation

(d)

Pulse width modulation

32.

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

(a)

(b)

(c)

(d)

33.

Emission of electrons by the absorption of heat energy is called ______ emission.

(a)

photoelectric

(b)

field

(c)

thermionic

(d)

secondary

34.

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

35.

A charge Q is placed at the corner of a cube. The electric flux through all the six faces of the cube is

(a)

\(\frac { Q }{ { 3\varepsilon }_{ 0 } } \)

(b)

\(\frac { Q }{ { 6\varepsilon }_{ 0 } } \)

(c)

\(\frac { Q }{ { 8\varepsilon }_{ 0 } } \)

(d)

\(\frac { Q }{ { \varepsilon }_{ 0 } } \)

36.

Value of k in Coulomb's law depends upon

(a)

magnitude of charges

(b)

distance between charges

(c)

both (a) and (b)

(d)

medium between two charges

37.

When 4V emf is applied across a 1F capacitor, it will store energy of

(a)

(b)

(c)

(d)

38.

A non-conducting material which has no free electrons is called

(a)

capacitor

(b)

Dielectric

(c)

conductor

(d)

Inductor

39.

Increasing the charge on the plates of a capacitor means ___________

(a)

increasing the capacitance

(b)

increasing the potential difference between the plates

(c)

both (a) and (b) above

(d)

none of the above

40.

A condenser is charged to a potential of 200V and has a charge of 0.1C. The energy stored in it is _____________

(a)

1 J

(b)

2 J

(c)

10 J

(d)

20 J

41.

The force experienced by a unit charge is called ____________

(a)

Electric potential

(b)

Electric flux

(c)

Electric field

(d)

Static electricity

42.

A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and the distance between the plates are each doubled then which is the quantity that will change?

(a)

Capacitance

(b)

Charge

(c)

Voltage

(d)

Energy density

43.

If voltage applied on a capacitor is increased from V to 2V, choose the correct conclusion.

(a)

Q remains the same, C is doubled

(b)

Q is doubled, C doubled

(c)

C remains same, Q doubled

(d)

Both Q and C remain same

44.

Rank the electrostatic potential energies for the given system of charges in increasing order

(a)

1 = 4 < 2 < 3

(b)

2 = 4 < 3 < 1

(c)

2 = 3 < 1 < 4

(d)

3 < 1 < 2 < 4

45.

Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric flux through each Gaussian surface in increasing order.

(a)

D < C < B < A

(b)

A < B = C < D

(c)

C < A = B < D

(d)

D > C > B > A

46.

An electric dipole is placed at an alignment angle of 30^o with an electric field of 2 x 10⁵ NC^-1. It experiences a torque equal to 8 N m. The charge on the dipole if the dipole length is 1 cm is

(a)

4 mC

(b)

8 mC

(c)

5 mC

(d)

7 mC

47.

Two identical point charges of magnitude –q are fixed as shown in the figure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement?

(a)

A₁ and A₂

(b)

B₁ and B₂

(c)

both directions

(d)

No stable

48.

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)

\(\frac{R}{2}\)

49.

A wire connected to a power supply of 230 V has power dissipation P₁. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P₂. The ratio \(\frac{P_2}{P_1}\) is ______.

(a)

(b)

(c)

(d)

50.

A wire of resistance 2 ohms per meter is bent to form a circle of radius 1m. The equivalent resistance between its two diametrically opposite points, A and B as shown in the figure is

(a)

\(\pi \Omega\)

(b)

\(\frac{\pi}{2}\Omega\)

(c)

2\(\pi \Omega\)

(d)

\(\frac{\pi}{4}\Omega\)

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Answers Key:

Multiple Choice Question

50 x 1 = 50

(b)
1

(d)
all of these

(a)
I_C and V_BE

(a)
I_B and V_BE

(b)
base

(d)
Twisted pair

10.

(a)
tank

11.

(a)
electrical, sound

12.

13.

(b)
AM

14.

(b)
sky

15.

(b)
vertical

16.

(d)
the frequency of modulated wave varies as frequency of modulating wave

17.

\(r_i=\frac{\Delta V_{\mathrm{BE}}}{\Delta \mathrm{I}_{\mathrm{in}}}=\frac{0.04}{40 \times 10^{-6}}=1 \mathrm{k} \Omega\)

18.

\( \mathrm{I}_{\mathrm{C}} =\beta \mathrm{I}_{\mathrm{B}} \)
\( =100 \times 100 \mu \mathrm{A} \)
\(\mathrm{I}_{\mathrm{C}} =10 \mathrm{~mA} \)

19.

20.

(b)
critical size

21.

(b)
α particle

22.

(a)
both the neutron number and the proton number change

23.

(d)
UV

24.

25.

26.

(b)
Stark effect

27.

(a)
in a circular orbit

28.

(b)
electric charge is quantised

29.

There are two type of Synthesis of nano materials:
(i) Bottom up - Assembling atoms together.
(ii) Top down Breaking down bulk solid.

30.

Parrot fish's source of bite → mimic → Ultra durable synthetic material.
Lotus leaf surface → SEM → Self Cleaning Process
The scales on the wings of a morpho butterfly → mimic → Interaction of colours.
Peacock feathers → mimic → Glowing in different colours.

31.

(b)
Frequency modulation

32.

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

33.

34.

(b)
get shifted upwards

35.

(d)
\(\frac { Q }{ { \varepsilon }_{ 0 } } \)

36.

(d)
medium between two charges

37.

(d)
8J

38.

(b)
Dielectric

39.

(b)
increasing the potential difference between the plates

40.

41.

42.

Energy density u_E \(=\frac{U}{volume}\)
If A' = 2A d ' = 2d
Then V ' = 2A x 2d = 4Ad = 4V
Then volume would be increased. So, energy density will change.

43.

If voltage is increased from V to 2 V
Then Q₁ = CV
Q₂ = C(2 V) = 2 CV
∴ Q is doubled and C remains same

44.

\(U=\frac{1}{4\piε_0}\frac{q_1q_2}{r_{12}}\)
\(i) U=\frac{1}{4\piε_0}\frac{Q(-Q)}{r}=\frac{1}{4\piε_0}[\frac{-Q^2}{r}]\)
\(ii) U=\frac{1}{4\piε_0}\frac{(-Q)(-Q)}{r}=\frac{1}{4\piε_0}[\frac{Q^2}{r}]\)
\(iii) U=\frac{1}{4\piε_0}\frac{Q(2Q)}{r}=\frac{1}{4\piε_0}[\frac{2Q^2}{r}]\)
\(iv) U=\frac{1}{4\piε_0}\frac{Q(-2Q)}{2r}=\frac{1}{4\piε_0}[\frac{-Q^2}{r}]\)
From the values, 1 = 4 < 2 < 3

45.

The electric flux of D is less than that of C
The electric flux of C is less than that of B
The electric flux of B is less than that of A

46.

(b)
8 mC

47.

The charge + q will be stable between B₁ and B₂ with respect to the displacement.

48.

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

49.

\(\mathrm{V}=230 \mathrm{~V} \)
\(P=\frac{V^2}{R} \text { since } \mathrm{V} \text { is same } \mathrm{P} \propto \frac{1}{R} \)
\(\frac{1}{R_2}=\frac{1}{\frac{R_1}{2}}+\frac{1}{\frac{R_1}{2}}=\frac{2}{R_1}+\frac{2}{R_1}=\frac{2+2}{R_1} \)
\(\frac{1}{R_2}=\frac{4}{R_1} \)
\(\therefore R_2=\frac{R_1}{4} \)
\(R_1=4 R_2 \)
\(\therefore \frac{P_2}{P_1}=\frac{R_1}{R_2}=\frac{4 R_2}{R_2}=4\)

50.

Total length = 2πr = 2π
∴ Resistance of each segment = 2π/2 = π Ω