A circular coil of 20 turns and radius 10 cm is placed in a uniform magnetic field of 0 · 10 T normal to the plane of the coil. If the current in the coil is 5 · 0 A , what is the total force on the coil,

As the circular loop is placed in uniform magnetic field which is perpendicular to its plane, so the forces on the opposite ends of its any diameter with be equal and opposite. Hence, the resultant force on the circular loop will be zero.

State Bohr’s postulate to define stable orbits in hydrogen atom. How does de Broglie’s hypothesis explain the stability of these orbits ?

Bohr's postulate to define stable orbits in hydrogen atoms states that an electron can revolve only in those circular orbits in which its angular momentum is an integral multiple of n h / 2 π , where h is Planck’s constant and n is the principal quantum number of orbit. Thus, an electron can revolve only in certain orbits of definite radii. These are called stable orbits. An atom has a number of stable orbits in which an electron can reside without the emission of radiant energy. Each orbit corresponds, to a certain energy level. De Broglie hypothesis explanation of the stability of orbits: According to de Broglie, an electron orbiting around the nucleus is associated with a stationary wave. Electron wave is a circular standing wave. Since destructive interference will occur if a standing wave does not close upon itself, only those de Broglie waves exist for which the circumference of the circular orbit contains a whole number of wavelengths i.e., the circumference of n t h stable orbit for an electron can contain exactly n wavelength of de-Broglie. ⇒ n λ = 2 πr n n h p = 2 πr n n h m v = 2 πr n m v r n = n h 2 π ⇒ L = n h 2 π This was the quantum condition proposed by Bohr.

A symmetric biconvex lens of the radius of curvature R and made of glass of refractive index 1 . 5 , is placed on a layer of liquid placed on top of a plane mirror as shown in the figure. An optical needle with its tip on the principal axis of the lens is moved along the axis until its real, inverted image coincides with the needle itself. The distance of the needle from the lens is measured to be x . On removing the liquid layer and repeating the experiment, the distance is found to be y . Obtain the expression for the refractive index of the liquid in terms of x and y .

We are given, the refractive index of the lens, μ g = 1 . 5 . The distance of the needle from the lens in the first case is equal to the focal length of the combination of a convex lens and a planoconcave lens formed by the liquid. Thus, f = x The distance measured in the second case is equal to the focal length of the convex lens. Thus, f 1 = y Let f 2 be the focal length of the planoconcave lens formed by the liquid. Then, 1 f = 1 f 1 + 1 f 2 1 f 2 = 1 x - 1 y = y - x x y f 2 = x y y - x Let the radius of curvature of the first surface be R The radius of curvature of the second surface will be - R Thus, for the biconvex lens, 1 f 1 = μ g - 1 1 R - 1 - R 1 y = 1 . 5 - 1 2 R ⇒ y = R Let the refractive index of liquid be μ . For plano-convex lens, R 2 = ∞ R 1 = - R Thus, 1 f 2 = μ - 1 1 - R - 1 ∞ Substituting values from above, y - x x y = μ - 1 1 - y μ - 1 = - ( y - x ) x μ = x - y x + 1 μ = 2 x - y x

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12th Karnataka Board

IMPORTANT

Earn 100

Write the colour coding scheme for a carbon resistor whose resistance is $2.4 \times 10^{6} ohm$ .

Important Questions on Solved Physics Paper-2

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 5

A circular coil of

20

turns and radius

10 cm

is placed in a uniform magnetic field of

0 \cdot 10 T

normal to the plane of the coil. If the current in the coil is

5 \cdot 0 A

, what is the total force on the coil,

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 6

State Gauss’ law for magnetism. Explain its significance.

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12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 7

A short bar magnet has a magnetic moment of

0.48 J T^{- 1}

. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of

10 cm

from the centre of the magnet on the equatorial lines (normal bisector) of the magnet.

HARD

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 8

A circuit containing a

80 m H

inductor and a

60 µ F

capacitor in series is connected to a

230 V

50 H z

supply. Suppose the circuit has a resistance of

15 Ω

. Obtain the average power transferred to each element of the circuit, and the total power absorbed.

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12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 9

When can a charge act as a source of electromagnetic wave?

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12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise>Q 10

Name the electromagnetic radiation to which the following wavelengths belong:
a) $10^{- 2} m$

b) $1 Å$

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12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise-Choice>Q 11

Two wavelengths of sodium light

590 nm

and

596 nm

are used, in turn, to study the diffraction taking place at a single slit of aperture

2 \times 10^{- 4} m

.
The distance between the slit and the screen is

1.5 m

. Calculate the separation between the positions of the first secondary maxima of the diffraction pattern obtained in the two cases.

MEDIUM

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 16 - Solved Physics Paper-2>Exercise-Choice>Q 12

Define resolving power of a compound microscope. On what factors does it depend ?

Write the colour coding scheme for a carbon resistor whose resistance is 2.4 × 106 ohm.

Important Questions on Solved Physics Paper-2

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Write the colour coding scheme for a carbon resistor whose resistance is $2.4 \times 10^{6} ohm$ .