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COMMON HALF – YEARLYPHYSICS KEY ANSWERS DECEMBER-2016 PART-I Sl. No 1

Answers

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Sl. No 16

Answers

A) 1:2:3 A)Zero C)Inside the sphere D) Current density C) H = VIt B) Work is doneon the electron B) Room heater D) Cosservation of energy

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A) 1000w B)Increase with increase in frequecy A) Pure line spectrum B)1:2 A) µ:1 A)1.732

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B)Continuous spectrum C) 20000cm-1 B) absorbs green light D) Charge B)Photon B)α particles B)200 MeV C)Different mass and same velocity C) 3.7x1010becquerel B) +1V

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C)Immobile positive ions A) Collision B) 0.03 MHz and 60 kHz D) 64 µs

C)

𝑎 𝜀𝑟

A) Stream of electrons

Important Note: 1. For answers in Part – II , Part-III, and Part- IV like reasoning , explanation, narration,description and listing the points, students may write in their own words but without changing the concepts and without skipping any point. 2. Answers written only in BLACK or BLUE should be evaluated. 3. For graphical representation, X and Y variables must be mentioned . If not , reduce ½ mark. 4. Marks should be given to the unit, only if the answer is correct for problems.

PART-II Q.No 31 32 33

Descrbtion Electric flux– Correct definition Nm2c-1 Polar and non-polar molecules any 3 differences(3x1) Faradays laws First law Second law (or) For mere equations of two laws mαq – 1 mark mαE – 1 mark

MARK TOTAL 2 1 3

3 3 3

1½ 1½

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Superconductors – correct definition 𝑅𝐴 𝑙

ρ = (or) ( related formula) substitution ρ = 1.9625x10-8Ωm(correct answer +unit) Peltier co-efficient Unit: volt Flemming’s Right hand rule- correct law e = -Blv substitution e = -1mV (correct answer +unit) Characteristics of Electromagnetic waves – any 3 (3x1) Optical activity –correct statement Examples-any 2 Hard X-rays and soft X-rays – differences- any 3(3x1) 𝑚𝑣 r= 𝐵𝑒 substitution r= 0.455 m (correct answer +unit) Inertial frames of references Non-inertial frames of references τ=1.44T½ substitution τ= 5.482 days(correct answer +unit) Properties of Neutron – any 3 (3x1) 𝐼𝑐 IB = 𝛽

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Substitution IB = 61.86 µA NPN TRANSISITOR IN CE MODE- DIAGRAM (without labeling only 2 marks) Methods of doping a semiconductors - any 3 (3x1) NAND and NOR gates are called Universal gates Because they can perform all the three basic logic functions Applications of RADAR –any 3 – (3x1)

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3 1 1 ½ +½

3 3

2 1 3 1 1 ½ +½ 3 2 1 3 1 1 ½ +½

3

1½ 1½ 1 1 ½ +½ 3 1 1 ½ +½

3

3

3

3 2 1 3

3 3

3 3

3 3 3 3

3

3 3

3

PART-III 51

Capacitors in Series Diagram Explanation V = V1+V2+V3 𝑞 𝑞 𝑞 1 1 1 V1=𝐶1 , V2=𝐶2, V3= 𝐶3 (OR) V = q( 𝐶1 + 𝐶2+𝐶3) 1 𝐶𝑆

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=

1 𝐶1

+

1 1 + 𝐶2 𝐶3

PROBLEM- RESISTORS 1 1 1 1 = 𝑅1 + 𝑅2+𝑅3 𝑅𝑝 Substitution

5 1 1 1 1 1 5 1 1

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Rp= 1 Ω V = IR Substitution I = 2A Daniel cell Diagram Construction Working Mentioning- cannot supply steady current for long time emf = 1.08 V µ𝑜𝐼1𝐼2𝑙

a) F= 2𝜋𝑎 and related formula Substitution F1= 24x10-5N F2= 40x10-5N The wire B is attracted towards C with a net force of 16x10-5N (or) b) τ = nBIA – ½ τ= C𝜃 - ½ C𝜃

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I= -1 𝑛𝐵𝐴 Substitution I = 0.166mA(correct answer +unit) Energy of an Inducor 𝑑𝐼 Explanation with e = -L 𝑑𝑡 dw = e I dt 𝐼𝑜 w = 𝑑𝑤 (or) W = 0 −𝐿𝐼𝑑𝐼 1

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E = - LIo2 2 Lenz’s law not mentioned reduce ½ mark λ = (rn+m)2- rn2/mR (or) related formula substitution and calculation λ=5645Å(correct answer +unit) Spectral series of Hydrogen atom Explanation of five series Formula (or) Mere mentioning the names of spectral series only Application of Photoelectric cells – any 5 (5x1) Time Dilation Explanation 𝑡𝑜 t= 2 𝑣

1− 2 𝑐

t > to lengthened factor

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5 1 1 2 ½ ½ 1 2 1 1 1

5

2 2

1 1 1 1 1

5

2 2 1

5

5 2½ 2½ 2 5 1 1

5 5

1 1

3

1 𝑣2 1− 2 𝑐

Example Properties of β-rays (5x1)

1 5

5

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DeMorgan theorem First statement Second statement (or) Only equations – 2 marks Proof using truth tables (or) any other method Monochrome TV receiver Block diagram 10 x ½ = 5

5 1½ 1½

2 5 5

PART - IV 63

Gauss’s law – long straight charged wire Gauss’s law – correct statement (or) Formula only – 1 mark Diagram Explanation ∅ = 𝐸 𝑑𝑠 𝑐𝑜𝑠𝜃 (or) E = (2πrl) E = (2πrl) Electric fiux through the plane cap = 0 q = λl 𝜆𝑙

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𝜆

E = (2πrl) = 𝜀𝑜 (or) E = 2𝜋𝜀𝑜𝑟 E is radially outward if line charge is positive and inward , if line charge is negative. Cyclotron Diagram Principle Construction Working BqV = mv2 / r T = 2 π m / Bq ( or ) ν = Bq / 2πm Limitations (any 2) Mutual Induction Diagram Mutual induction – correct statement Explanation of mutual induction Mutual Induction of two long solenoid Diagram Explanation Upto∅2 = MI1 𝜇𝑁 1𝑁2𝐴 MI1 = 𝑙 Raman effect Raman effect – explanation Diagram (3x1) Explanation of stoke’s and Anti-stoke’s lines with respect to frequency

10 2 1 2 1 1 ½ ½ 1 1 10 2 1 1½ 1½ 1 1 2 10 1 1 3 1 1 2 1 10 1 3 1

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Explanation of Raman effect (3x1) Explanation for ∆ν = νo-νs ∆ν is positive for stoke line ∆ν is negative for Anti-stoke line Intensity of stoke line is always greater than antistoke line Bragg’s Law with Bragg’s spectrometer Bragg’s Law Diagram Explanation - Experiments Graph Graph explanation GM Counter Principle Diagram Construction( reduce 1 mark if any one of the following is missing 1000V and 100MΩ ) working Ionization of the gas is independent of type incident radiation Output characteristics of NPN Transistor in CE Mode Diagram Output Graph Explanation Saturation region Cut off region Active region Output impedence – definition Formula Output impedenceof a transistor in CE Mode is low Vidicon camera tube Diagram with parts Principle : Photo conductivity (or) Converts light energy into electrical energy Construction Working

3 1

1 10 2 2 3 1½ 1½ 10 1 2 3 3 1 10 2 2 1 1 1 1 1 ½ ½ 10 3 1 3 3

PREPARED BY

B.KANNAN M.Sc., B.Ed., BT ASST IN SCIENCE ,GHSS, MUDUR, VELLORE – 631 003 5

B.KANNAN M.Sc., B.Ed.,GHSS MUDUR, VELLORE-631 003|