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12th Standard Physics English Medium Important 1 Mark Book Back Questions (New Syllabus) 2020

Published on: 25/08/2020

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.

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Std: 12th Standard - Physics

chapter: - Model Question paper

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Questions:

Multiple Choice Question

24 x 1 = 24

Nanoscience is the science of object with typical sizes of ___________

(a)

1 - 100 μ

(b)

1 - 100 nm

(c)

1 - 100 cm

(d)

1- 100 m

The made of propagation used by short wave broadcast services is _______________.

(a)

space wave

(b)

skywave

(c)

ground wave

(d)

both (a) & (c)

For base station to mobile communication, the required frequency band is _____________.

(a)

540 - 1600 KHz

(b)

200 - 32 MHz

(c)

840 - 935 MHz

(d)

5.9 - 6.42 GHz

Which of the following is an example of breadcast made of communication?

(a)

Radio

(b)

Television

(c)

Mobile

(d)

both (a) & (b)

The materials used in Robotics are _____.

(a)

Aluminium and silver

(b)

Silver and gold

(c)

Copper and gold

(d)

Steel and aluminum

The internationally accepted frequency deviation for the purpose of FM broadcasts ____________.

(a)

75 kHz

(b)

68 kHz

(c)

80 kHz

(d)

70 kHz

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

The charge of cathode rays particle is _____.

(a)

Positive

(b)

negative

(c)

neutral

(d)

not defined

If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is _____.(Take h = 6.6 x 10^–34 Js)

(a)

< 2.75 ×10⁻⁹m

(b)

≥ 2.75 × 10⁻⁹m

(c)

≤ 2.75 × 10⁻¹²m

(d)

< 2.5 × 10⁻¹⁰m

10.

The wave associated with a moving particle of mass 3 x 10^–6 g has the same wavelength as an electron moving with a velocity 6 x 10⁶ ms^-1. The velocity of the particle is _____.

(a)

1.82 x 10^-18ms^-1

(b)

9 x 10^-2ms^-1

(c)

3 x 10^-31ms^-1

(d)

1.82 x 10^-15ms^-1

11.

A ray of light strikes a glass plate at an angle 60^o. If the reflected and refracted rays are perpendicular to each other, the refractive index of the glass is, _____.

(a)

\(\sqrt3\)

(b)

\(\frac{3}{2}\)

(c)

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

(d)

12.

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)

\(\frac{{V_a}\lambda_a}{{V_W}\lambda_W}\)

13.

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

14.

A circular coil of radius 5 cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of the coil is nearly ____.

(a)

1.0 A m²

(b)

1.2 A m²

(c)

0.5 A m²

(d)

0.8 A m²

15.

A circular coil with a cross-sectional area of 4 cm² has 10 turns. It is placed at the centre of a long solenoid that has 15 turns/cm and a cross-sectional area of 10 cm². The axis of the coil coincides with the axis of the solenoid. What is their mutual inductance?

(a)

7.54 μH

(b)

8.54 μH

(c)

9.54 μH

(d)

10.54 μH

16.

A thin semi-circular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure.

The potential difference developed across the ring when its speed v, is

(a)

Zero

(b)

\(\frac { { Bv\pi { r }^{ 2 } } }{ 2 } \) and P is at higher potential

(c)

πrBv and R is at higher potential

(d)

2rBv and R is at higher potential

17.

Which of the following is NOT true for electromagnetic waves?

(a)

it transport energy

(b)

it transport momentum

(c)

it transport angular momentum

(d)

in vacuum, it travels with different speeds which depend on their frequency

18.

If E = E_o sin[10⁶ x -ωt] be the electric field of a plane electromagnetic wave, the value of ω is_____.

(a)

0.3 x 10⁻¹⁴ rad s⁻¹

(b)

3 x 10⁻¹⁴ rad s⁻¹

(c)

0.3 x 10¹⁴ rad s⁻¹

(d)

3 x 10¹⁴ rad s^-1

19.

Which of the following is false for electromagnetic waves

(a)

transverse

(b)

non-mechanical waves

(c)

longitudinal

(d)

produced by accelerating charges

20.

Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be _____.

(a)

less than before

(b)

same as before

(c)

more than before

(d)

zero

21.

Which charge configuration produces a uniform electric field?

(a)

point charge

(b)

uniformly charged infinite line

(c)

uniformly charged infinite plane

(d)

uniformly charged spherical shell

22.

In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW are connected. The voltage of electric mains is 220 V. The maximum capacity of the main fuse of the building will be ______.

(a)

14 A

(b)

8 A

(c)

10 A

(d)

12 A

23.

What is the value of resistance of the following resistor?

(a)

100 k Ω

(b)

10 k Ω

(c)

1 k Ω

(d)

1000 k Ω

24.

A toaster operating at 240 V has a resistance of 120 Ω. The power is ______.

(a)

400 W

(b)

2 W

(c)

480 W

(d)

240 W

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Answers Key:

Multiple Choice Question

24 x 1 = 24

(b)
1 - 100 nm

(b)
skywave

(d)
both (a) & (b)

(d)
Steel and aluminum

(a)
75 kHz

Cathode rays are stream of negatively charged electron.

(b)
≥ 2.75 × 10⁻⁹m

10.

\(\lambda_{\mathrm{i}} \frac{1}{\mathrm{mv}} \)
\(\frac{\lambda_p}{\lambda_e} =\frac{m_e v_e}{m_P v_P} \)
\(1 =\frac{9.1 \times 10^{-31} \times 6 \times 10^6}{3 \times 10^{-9} \times v_p} \)
\(\mathrm{v}_{\mathrm{p}} =9.1 \times 10^{-16} \times 2 \)
\(\mathrm{v}_{\mathrm{p}} =18.2 \times 10^{-16} \)
\(\mathrm{v}_{\mathrm{p}} =1.82 \times 10^{-15} \mathrm{~m} \mathrm{~s}^{-1}\)

11.

n = tan i_p = tan 60^o = \(\sqrt{3}\)

12.

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

13.

(a)
Circle

14.

Dipole moment, \(\vec{p}_m=n\times I\times\vec{A}\)
\(\vec{p}_m\) = 50 x 3 x 3.14 x 25 x 10^-4 ≈ 1.2 A m²

15.

\(A_1 =4 \times 10^{-4} \mathrm{~m}^2 \)
\(N_1 =10 \text { turns } \)
\(A_2 =4 \times 10^{-4} \mathrm{~m}^2 \)
\(N_2 =15 \times 10^{-}=1500 \mathrm{turn} / \mathrm{m} \)
\(\phi =B_2 A_2=\left(\mu_0 \mathrm{n}_2 I_2\right) \mathrm{A}_1 \)
\(Where, \mathrm{n}_2=\frac{\mathrm{N}_2}{l}=1500 \mathrm{turn} / \mathrm{m}\)
The mutual Inductance is,
\(M =\frac{N_1 o_{12}}{I_2}=\mu_0 n_2 N_1 A_1 \)
\(=4 \pi \times 10^{-7} \times 1500 \times 10 \times 4 \times 10^{-4} \)
\(=7.54 \times 10^{-6} \mathrm{H}=7.54 \mu \mathrm{H}\)

16.

(d)
2rBv and R is at higher potential

17.

(d)
in vacuum, it travels with different speeds which depend on their frequency

18.

E = E_o sin(kx – ωt)
ω = ck
ω = 3 x 10⁸ x 10⁶
ω = 3 x 10¹⁴ rad s^-1

19.

20.

Force ∝ charge
After the separation, the magnitude of charge will be increased. So the force will be more than before.

21.

22.

Total power = 15 x 40 + 5 x 100 + 5 x 80 + 1000
= 600 + 500 + 400 + 1000
= 2500 W
P = VI, V = 220 V
\(I=\frac{P}{V}=\frac{2500}{220}=11.363 \ A\)
≃ 12 A

23.

Brown - 1
Black - 0
Yellow - 10⁴
(∴ R = 10 x 10⁴ Ω = 100 kΩ)

24.

\(P=\frac{V^2}{R}=\frac{240 \times 240}{120}=480 \ W\)