A uniform magnetic field gets modified as shown in figure when two specimens A and B are placed in it. (i) Identify the specimen A and B. (ii) How is the magnetic susceptibility of specimen A different from that of specimen B?

Magnetic lines of force is defined as the imaginary path along which an imaginary magnetic north pole can move if placed in a magnetic field. (i) From figure (a), it can be seen that the magnetic lines of forces are repelled by the material. Hence, the nature of the material is diamagnetic. From figure (b), it can be seen that the magnetic lines of force are attracted by the material given. Hence, the nature is paramagnetic. (ii) The main difference between the susceptibilities of these two materials is that for diamagnetic material the susceptibility is small and negative, whereas in case of paramagnetic material, the susceptibility is small and positive.

What is the nuclear radius of 125 Fe , if that of 27 Al is 3 . 6 fermi ?

The nuclear radius of an element is directly proportional to one-third of its atomic number. The formula to calculate the nuclear radius is given by R = R 0 A 1 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . ( 1 ) where, R is the nuclear radius, A is its atomic number and R 0 is a constant. Substitute 3 . 6 for R and 27 for A into equation (1) for aluminium and solve to calculate the value of the constant. 3 . 6 = R 0 27 1 3 R 0 = 3 . 6 27 1 3 = 1 . 2 Substitute 1 . 2 for R 0 and 125 for A into equation (1) to calculate the atomic radius of Iron. R = 1 . 2 × 125 1 3 fermi = 6 . 0 fermi

The short wavelength limit for the Lyman series of the hydrogen spectrum is 913 . 4 A ∘ . Calculate the short wavelength limit for the Balmer series of the hydrogen spectrum.

The frequency of an electronic transition is inversely proportional to the square of the principal quantum number. In atomic spectra, Lyman series corresponds to the transition of electron from n = ∞ to n = 1 state, whereas the Balmer series corresponding to the transition of electron from n = ∞ to n = 2 state. The formula to calculate the wavelength of the transition of electron from n 2 to n 1 is given by 1 λ = R 1 n 2 2 - 1 n 1 2 . . . . . . . . . . . . . . . . . . . . . . . . . . ( 1 ) where, R is called the Rydberg's constant. Substitute ∞ for n 1 , 1 for n 2 and 913 . 4 for λ into equation (1) and simplify to obtain the value of the Rydberg's constant. 1 913 . 4 = R 1 1 2 - 1 ∞ R = 1 913 . 4 Substitute ∞ for n 1 , 2 for n 2 and the value of R into equation (1) and solve to calculate the required wavelength corresponding to Balmer series. 1 λ = 1 913 . 4 × 1 2 2 - 1 ∞ λ = 4 × 913 . 4 = 3653 . 6 fermi

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If the rating of the voltmeter $V_{1}$ is $40 V$ , then the reading of the voltmeter $V_{2}$ is

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 15

The electric potential $V$ as a function of distance $X$ is shown in the figure.

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The graph of the magnitude of electric field intensity $E$ as a function of $X$ is

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 19

Electromagnetic waves with wavelength
(i)

λ_{1}

is suitable for radar systems used in aircraft navigation.
(ii)

λ_{2}

is used to kill germs in water purifiers.
(iii)

λ_{3}

is used to improve visibility in runways during fog and mist conditions.
Identify and name the part of the electromagnetic spectrum to which these radiations belong.Also arrange these wavelengths in ascending order of their magnitude.

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 20

A uniform magnetic field gets modified as shown in figure when two specimens A and B are placed in it.

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(i) Identify the specimen A and B.

(ii) How is the magnetic susceptibility of specimen A different from that of specimen B?

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 21

What is the nuclear radius of

^{125} Fe

, if that of

^{27} Al

3.6 fermi

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 22

The short wavelength limit for the Lyman series of the hydrogen spectrum is

913.4 \overset{\circ}{A}

. Calculate the short wavelength limit for the Balmer series of the hydrogen spectrum.

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 23

A biconvex lens made of a transparent material of refractive index

1.25

is immersed in water of refractive index

1.33

. Will the lens behave as a converging or a diverging lens? Justify your answer.

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 24

The figure shows a piece of pure semiconductor S in series with a variable resistor R and a source of constant voltage V. Should the value of R be increased or decreased to keep the reading of the ammeter constant, when semiconductor S is heated? Justify your answer.

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Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 15 - Sample Paper 1>Exercise>Q 25

The graph of potential barrier versus width of depletion region for an unbiased diode is shown in graph A. In comparison to A, graphs B and C are obtained after biasing the diode in different ways. Identify the type of biasing in B and C and justify your answer.

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If the rating of the voltmeter V1 is 40 V, then the reading of the voltmeter V2 is

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If the rating of the voltmeter $V_{1}$ is $40 V$ , then the reading of the voltmeter $V_{2}$ is