Title 11. DUAL NATURE OF RADIATION AND MATTER.pdf ✅

BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 11. DUAL NATURE OF RADIATION AND MATTER #QID# 33765 (1.) The ratio of the energy of an X-ray photon of wavelength 1 Å to that of visible light of wavelength 5000 Å is (a.) 1 :5000 (b.) 5000 :1 (c.) 1: 25 × 106 (d.) 25 × 106 Ans: b Exp: (b) Energy E = hv = h c λ ∴ E1 E2 = λ2 λ1 = 5000 1 #QID# 33766 (2.) If light of wavelength λ1 is allowed to fall on a metal, then kinetic energy of photoelectrons emitted is E1 . If wavelength of light changes to λ2 then kinetic energy of electrons changes to E2 . Then work function of the metal is (a.) E1E2(λ1−λ2) λ1λ2 (b.) E1λ1−E2λ2 (λ1−λ2) (c.) E1λ1−E2λ2 (λ2−λ1) (d.) λ1λ2E1E2 (λ2−λ1) Ans: c Exp: (c) E = W0 + Kmax ⇒ hc λ1 = W0 + E1 and hc λ2 = W0 + E2 ⇒ hc = W0λ1 + E1λ1 and hc = W0λ2 + E2λ2 ⇒ W0λ1 + E1λ1 = W0λ2 + E2λ2 ⇒ W0 = E1λ1 − E2λ2 (λ2 − λ1)
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 #QID# 33767 (3.) When two different materials A and B having atomic number Z1 and Z2 are used as the target in Coolidge γ-ray tube at different operating voltage V1 and V2 respectively their spectrums are found as below. The correct relation is (a.) V1 > V2 and Z1 > Z2 (b.) V1 < V2 and Z1 < Z2 (c.) V1 < V2 and Z1 > Z2 (d.) V1 > V2 and Z1 < Z2 Ans: d Exp: (d) λ min = hc eV ⇒ λ ∝ 1 V ∵ λ2 > λ1 (see graph) ⇒ V1 > V2 √v = a(Z − b) Moseley’s law v ∝ (Z − 1) 2 ⇒ λ ∝ 1 (Z−1)2 (∵ v ∝ 1 λ ) λ1 > λ2 (see graph for characteristic lines) ⇒ Z2 > Z1 #QID# 33768 (4.) If the linear momentum of a particle is 2.2 × 104 kg-ms −1 , then what will be its de-Broglie wavelength? (Take h = 6.6 × 10−34 Js) (a.) 3 × 10−29m
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 (b.) 3 × 10−29nm (c.) 6 × 10−29m (d.) 6 × 10−29nm Ans: b Exp: (b) Given, the linear momentum of particle (p) = 2.2 × 104kg − ms−1 h = 6.6 × 10−34 JS The de-Broglie wavelength of particle λ = h p λ = 6.6×10−34 2.2×104 Or λ = 3 × 10−38 m Or λ = 3 × 10−29 mm #QID# 33769 (5.) The rest mass of the photon is (a.) 0 (b.) ∞ (c.) Between 0 and ∞ (d.) Equal to that of an electron Ans: a #QID# 33770 (6.) The value of Plank energy is (a.) nhc λ (b.) nhλ (c.) nhcλ (d.) nhλ c Ans: a #QID# 33771
BUY COURSE FROM STORE TO GET INSTANT ANSWER AND EXPLANATION OF EACH QUESTION SPARK PCMB | DOWNLOAD APP NOW| +91-920-630-6398 (7.) The ratio of specific charge of an α-particle to that of a proton is (a.) 2 :1 (b.) 1 :1 (c.) 1 :2 (d.) 1 :3 Ans: c Exp: (c) Specific charge = q m ; Ratio = ( q m ) α ( q m ) p = qα qp × mp mα = 1 2 #QID# 33772 (8.) The correct graph between the maximum energy of a photoelectron and the inverse of wavelength of the incident radiation is given by the curve (a.) A (b.) B (c.) C (d.) None of the above Ans: a Exp: (a) Kmax = hv − hv0 = hc λ − hc λ0 , i. e., graph between Kmax and 1 λ will be straight line having slope (hc) and intercept hc λ0 on −KE axis #QID# 33773 (9.) Two identical metal plates shown photoelectric effect by a light of wavelength λÅ falls on plate A and λB on plate B(λA = 2λB ). The maximum kinetic energy is (a.) 2 KA = KB (b.) KA < KB/2 (c.) KA = 2KB (d.) KA = KB/2 Ans: b Exp: (b)