Page 1 CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 CBSE Class XII Physics – Set 1 Board Paper – All India – 2017 Solution SECTION A 1. Nichrome wire is heated more ? ? 22 nichrome copper nichrome copper Heat dissipate in a wire is given by H I Rt I t A H I, and A remains same But HH ? ?? ? ? ? ? ? ? ?? 2. Yes. As an electromagnetic wave is a combination of electric and magnetic fields, it carries both energy and momentum. It is given by hC E p mC ? ? ? where c = Speed of EM wave in vacuum ? = Wavelength of EM wave 3. If the incident violet light is replaced with red light, then the angle of minimum deviation of a glass prism decreases. 4. Photoelectric effect shows the quantum nature of electromagnetic radiation. 5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate B, i.e. polarity of Plate A will be positive with respect to Plate B. Page 2 CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 CBSE Class XII Physics – Set 1 Board Paper – All India – 2017 Solution SECTION A 1. Nichrome wire is heated more ? ? 22 nichrome copper nichrome copper Heat dissipate in a wire is given by H I Rt I t A H I, and A remains same But HH ? ?? ? ? ? ? ? ? ?? 2. Yes. As an electromagnetic wave is a combination of electric and magnetic fields, it carries both energy and momentum. It is given by hC E p mC ? ? ? where c = Speed of EM wave in vacuum ? = Wavelength of EM wave 3. If the incident violet light is replaced with red light, then the angle of minimum deviation of a glass prism decreases. 4. Photoelectric effect shows the quantum nature of electromagnetic radiation. 5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate B, i.e. polarity of Plate A will be positive with respect to Plate B. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 SECTION B 6. Intensity distribution graph for single slit diffraction Difference between interference pattern and diffraction pattern Interference Diffraction It is due to the superposition of two waves coming from two coherent sources. It is due to the superposition of secondary wavelets originating from different parts of the same wavefront. Width of the interference bands is equal. Width of diffraction bands is not the same. Page 3 CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 CBSE Class XII Physics – Set 1 Board Paper – All India – 2017 Solution SECTION A 1. Nichrome wire is heated more ? ? 22 nichrome copper nichrome copper Heat dissipate in a wire is given by H I Rt I t A H I, and A remains same But HH ? ?? ? ? ? ? ? ? ?? 2. Yes. As an electromagnetic wave is a combination of electric and magnetic fields, it carries both energy and momentum. It is given by hC E p mC ? ? ? where c = Speed of EM wave in vacuum ? = Wavelength of EM wave 3. If the incident violet light is replaced with red light, then the angle of minimum deviation of a glass prism decreases. 4. Photoelectric effect shows the quantum nature of electromagnetic radiation. 5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate B, i.e. polarity of Plate A will be positive with respect to Plate B. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 SECTION B 6. Intensity distribution graph for single slit diffraction Difference between interference pattern and diffraction pattern Interference Diffraction It is due to the superposition of two waves coming from two coherent sources. It is due to the superposition of secondary wavelets originating from different parts of the same wavefront. Width of the interference bands is equal. Width of diffraction bands is not the same. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 OR According to law of Malus, when a beam of completely plane polarised light is incident on an analyser ?, resultant intensity of light (I) transmitted from the analyser varies directly as the square of cosine of angle between the plane of the analyser and polariser. ? ? ? ? ? ? ? ? 2 2 o o I cos I I cos ........ Equation 1 When 0 or 180 cos 1 I I ........ Equation 2 When 90 c polarizer and anal os cos90 0 yzer and parallel In unpolarised light, I 0 ........ Equati vib on 3 ?? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ?? ? ?? ?? ? ? ? 2 av 2 0 2 2 0 rations are probable in all the direction in a plane perpendicular to the direction of propa cos gation cos 1 cos2 2 . can have any value from 0 and 2 . 1 d 2 1 2 d ? ? ? ? ? ? ?? ?? ?? ?? ?? ? ? ? ? ? ? ? ? 2 0 2 o o o sin2 0 2 1 22 1 2 Using the law of malu I I cos s 1 2 I I 2 I ? ?? ? ? ?? ?? ?? ?? ? ? ? ? ?? ? ? Graph: Page 4 CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 CBSE Class XII Physics – Set 1 Board Paper – All India – 2017 Solution SECTION A 1. Nichrome wire is heated more ? ? 22 nichrome copper nichrome copper Heat dissipate in a wire is given by H I Rt I t A H I, and A remains same But HH ? ?? ? ? ? ? ? ? ?? 2. Yes. As an electromagnetic wave is a combination of electric and magnetic fields, it carries both energy and momentum. It is given by hC E p mC ? ? ? where c = Speed of EM wave in vacuum ? = Wavelength of EM wave 3. If the incident violet light is replaced with red light, then the angle of minimum deviation of a glass prism decreases. 4. Photoelectric effect shows the quantum nature of electromagnetic radiation. 5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate B, i.e. polarity of Plate A will be positive with respect to Plate B. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 SECTION B 6. Intensity distribution graph for single slit diffraction Difference between interference pattern and diffraction pattern Interference Diffraction It is due to the superposition of two waves coming from two coherent sources. It is due to the superposition of secondary wavelets originating from different parts of the same wavefront. Width of the interference bands is equal. Width of diffraction bands is not the same. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 OR According to law of Malus, when a beam of completely plane polarised light is incident on an analyser ?, resultant intensity of light (I) transmitted from the analyser varies directly as the square of cosine of angle between the plane of the analyser and polariser. ? ? ? ? ? ? ? ? 2 2 o o I cos I I cos ........ Equation 1 When 0 or 180 cos 1 I I ........ Equation 2 When 90 c polarizer and anal os cos90 0 yzer and parallel In unpolarised light, I 0 ........ Equati vib on 3 ?? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ?? ? ?? ?? ? ? ? 2 av 2 0 2 2 0 rations are probable in all the direction in a plane perpendicular to the direction of propa cos gation cos 1 cos2 2 . can have any value from 0 and 2 . 1 d 2 1 2 d ? ? ? ? ? ? ?? ?? ?? ?? ?? ? ? ? ? ? ? ? ? 2 0 2 o o o sin2 0 2 1 22 1 2 Using the law of malu I I cos s 1 2 I I 2 I ? ?? ? ? ?? ?? ?? ?? ? ? ? ? ?? ? ? Graph: CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 7. (a) X-rays: Used as a diagnostic tool in medicine and as a treatment for certain forms of cancer. (b) Microwaves: Used in radar systems in aircraft navigation. 8. Consider a charge q moving with velocity v in the presence of electric and magnetic fields. The force on an electric charge q due to both of them is ? ? ? ? ? ? ? ? ? ? electric magnetic where v velocity of the charge r location of the charge at a given time F q E r v B r F F F ........ Equation 1 = t E r Electric field B r Magnetic field ?? ? ? ? ?? ? ? ? ? ? ? Let us consider a simple case in which electric and magnetic fields are perpendicular to each other and also perpendicular to the velocity of the particle. ? ? E B F qE qEj.F q v B ˆ q vi Bk qBj ? ? ?? ?? ?? ? ? F q E vB j ? ? ? Thus, electric and magnetic forces are in opposite directions. Suppose we adjust the values of E and B such that magnitudes of the two forces are equal, then the total force on the charge is zero and the charge will move in the fields undeflected. This happens when Page 5 CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 CBSE Class XII Physics – Set 1 Board Paper – All India – 2017 Solution SECTION A 1. Nichrome wire is heated more ? ? 22 nichrome copper nichrome copper Heat dissipate in a wire is given by H I Rt I t A H I, and A remains same But HH ? ?? ? ? ? ? ? ? ?? 2. Yes. As an electromagnetic wave is a combination of electric and magnetic fields, it carries both energy and momentum. It is given by hC E p mC ? ? ? where c = Speed of EM wave in vacuum ? = Wavelength of EM wave 3. If the incident violet light is replaced with red light, then the angle of minimum deviation of a glass prism decreases. 4. Photoelectric effect shows the quantum nature of electromagnetic radiation. 5. According to Lenz law, Plate A of the capacitor is at a higher potential than Plate B, i.e. polarity of Plate A will be positive with respect to Plate B. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 SECTION B 6. Intensity distribution graph for single slit diffraction Difference between interference pattern and diffraction pattern Interference Diffraction It is due to the superposition of two waves coming from two coherent sources. It is due to the superposition of secondary wavelets originating from different parts of the same wavefront. Width of the interference bands is equal. Width of diffraction bands is not the same. CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 OR According to law of Malus, when a beam of completely plane polarised light is incident on an analyser ?, resultant intensity of light (I) transmitted from the analyser varies directly as the square of cosine of angle between the plane of the analyser and polariser. ? ? ? ? ? ? ? ? 2 2 o o I cos I I cos ........ Equation 1 When 0 or 180 cos 1 I I ........ Equation 2 When 90 c polarizer and anal os cos90 0 yzer and parallel In unpolarised light, I 0 ........ Equati vib on 3 ?? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ?? ? ?? ?? ? ? ? 2 av 2 0 2 2 0 rations are probable in all the direction in a plane perpendicular to the direction of propa cos gation cos 1 cos2 2 . can have any value from 0 and 2 . 1 d 2 1 2 d ? ? ? ? ? ? ?? ?? ?? ?? ?? ? ? ? ? ? ? ? ? 2 0 2 o o o sin2 0 2 1 22 1 2 Using the law of malu I I cos s 1 2 I I 2 I ? ?? ? ? ?? ?? ?? ?? ? ? ? ? ?? ? ? Graph: CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 7. (a) X-rays: Used as a diagnostic tool in medicine and as a treatment for certain forms of cancer. (b) Microwaves: Used in radar systems in aircraft navigation. 8. Consider a charge q moving with velocity v in the presence of electric and magnetic fields. The force on an electric charge q due to both of them is ? ? ? ? ? ? ? ? ? ? electric magnetic where v velocity of the charge r location of the charge at a given time F q E r v B r F F F ........ Equation 1 = t E r Electric field B r Magnetic field ?? ? ? ? ?? ? ? ? ? ? ? Let us consider a simple case in which electric and magnetic fields are perpendicular to each other and also perpendicular to the velocity of the particle. ? ? E B F qE qEj.F q v B ˆ q vi Bk qBj ? ? ?? ?? ?? ? ? F q E vB j ? ? ? Thus, electric and magnetic forces are in opposite directions. Suppose we adjust the values of E and B such that magnitudes of the two forces are equal, then the total force on the charge is zero and the charge will move in the fields undeflected. This happens when CBSE XII | PHYSICS Board Paper – All India – Set 1 – Solution 2017 qE = qvB or E or v B ? This condition can be used to select charged particles of a particular velocity out of a beam containing charges moving with different speeds (irrespective of their charge and mass). The crossed E and B fields therefore serve as a velocity selector. 9. It is given that the energy of the electron beam used to bombard gaseous hydrogen at room temperature is 12.5 eV. Also, the energy of the gaseous hydrogen in its ground state at room temperature is -13.6 eV. When gaseous hydrogen is bombarded with an electron beam, the energy of the gaseous hydrogen becomes -13.6 + 12.5 eV = -1.1 eV. Orbital energy related to orbit level (n) is ? ? ? ? 2 2 13.6 E eV n For n 3, 13.6 13.6 E eV eV 1.5 eV 9 3 ? ? ? ?? ? ? ? ? ? This energy is approximately equal to the energy of gaseous hydrogen. This implies that the electron has jumped from n = 1 to n = 3 level. During its de-excitation, electrons can jump from n = 3 to n = 1 directly, which forms a line of the Lyman series of the hydrogen spectrum. Relation for wave number for the Lyman series is ? ? ? ? 22 22 1 7 1 7 1 7 7 1 1 1 1 1 R 1n For first member n 3 1 1 1 1 1 RR 19 1 3 1 9 1 1.097 10 ......... 9 where Rydberg constant R 1. 18 1.097 10 9 1.025 10 097 10 m m ? ? ?? ?? ?? ?? ? ?? ? ?? ?? ?? ? ? ? ? ? ?? ? ?? ?? ?? ? ?? ? ? ? ?? ? ?? ? ? ? ? ? ? ? ? ?Read More

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