33 Years NEET-AIPMT Chapterwise Solutions - Physics 2020

Telegram @unacademyplusdiscounts
100 NEET-AIPMT Chapterwise Topicwise Solutions Physics
56. If a photon has velocity c and frequency u, then
which of the following represents its wavelength?
(a)
hυ
(b) hu (c)
hc
(d) h υ
2
c
E
c (1996)
57. The velocity of photons is proportional to (where
u = frequency)
(a) 1/ υ (b) u 2 (c) u (d) υ
(1996)
58. Momentum of photon of wavelength l is
(a) h (b) zero (c)
cυ h λ
(d) h λ
2
c
c (1993)
59. The wavelength of a 1 keV photon is 1.24 × 10 –9 m.
What is the frequency of 1 MeV photon?
(a) 1.24 × 10 15 (b) 2.4 × 10 20
(c) 1.24 × 10 18 (d) 2.4 × 10 23 (1991)
60. A radio transmitter operates at a frequency
880 kHz and a power of 10 kW. The number of
photons emitted per second is
(a) 1.72 × 10 31 (b) 1.327 × 10 25
(c) 1.327 × 10 37 (d) 1.327 × 10 45 (1990)
61. The momentum of a photon of an electromagnetic
radiation is 3.3 ×10 –29 kg m s –1 . What is the frequency
of the associated waves? [h = 6.6 × 10 –34 J s ;
c = 3 × 10 8 m s –1 ]
(a) 1.5 × 10 13 Hz (b) 7.5 × 10 12 Hz
(c) 6 × 10 3 Hz (d) 3 × 10 3 Hz (1990)
62. The energy of a photon of wavelength l is
(a) hcl (b) hc λ
(c) (d) λh
λ
hc
c (1988)
11.8 Wave Nature of Matter
63. An electron is accelerated from rest through a
potential difference of V volt. If the de Broglie
wavelength of the electron is 1.227 × 10 –2 nm, the
potential difference is
(a) 10 V
(b) 10 2 V
(c) 10 3 V (d) 10 4 V (NEET 2020)
64. An electron is accelerated through a potential
difference of 10,000 V. Its de Broglie wavelength is,
(nearly) (m e = 9 × 10 –31 kg)
(a) 12.2 nm
(c) 12.2 × 10 –12 m
(b) 12.2 × 10 –13 m
(d) 12.2 × 10 –14 m
(NEET 2019)
65. An electron of mass m with an initial velocity
^ ^
v = v0 i ( v0 > 0 ) enters an electric field E=−E 0 i
(E 0 = constant > 0) at t = 0. If l 0 is its de-Broglie
wavelength initially, then its de- Broglie wavelength
at time t is
λ
(a) 0 ⎛ eE
(b)
0 ⎞
λ
⎛ eE
1+
0 ⎞
0 1+
⎝
⎜ mv t ⎝
⎜
mv t
0 ⎠
⎟
0 ⎠
⎟
(c) l 0 t (d) l 0 (NEET 2018)
66. The de-Broglie wavelength of a neutron in thermal
equilibrium with heavy water at a temperature
T (kelvin) and mass m, is
h
2h
(a)
(b)
3mkT
3mkT
2h
h
(c)
(d)
mkT
mkT (NEET 2017)
67. Electrons of mass m with de-Broglie wavelength
l fall on the target in an X-ray tube. The cutoff
wavelength (l 0 ) of the emitted X-ray is
2
2 λ
(a) λ0
= mc h
2 2 3
2 λ
(c) λ0
= mc
2
h
(b) λ 0
2
= h
mc
(d) l 0 = l
(NEET-II 2016)
68. An electron of mass m and a photon have same
energy E. The ratio of de-Broglie wavelengths
associated with them is
1
1
(a) c( 2mE)
2 (b) 1 ⎛ 2 m ⎞ 2
c ⎝
⎜
E ⎠
⎟
1
1
(c) 1 ⎛ E ⎞ 2
⎛ E ⎞ 2
c ⎝
⎜
2m
⎠
⎟ (d)
⎝
⎜
2m ⎠
⎟
(c being velocity of light) (NEET-I 2016)
69. Light of wavelength 500 nm is incident on a
metal with work function 2.28 eV. The de Broglie
wavelength of the emitted electron is
(a) ≥ 2.8 × 10 –9 m (b) ≤ 2.8 × 10 –12 m
(c) < 2.8 × 10 –10 m (d) < 2.8 × 10 –9 m
(2015)
70. Which of the following figures represent the
variation of particle momentum and the associated
de-Broglie wavelength?
(a)
(c)
(b)
(d)
(2015 Cancelled)
71. If the kinetic energy of the particle is increased to 16
times its previous value, the percentage change in
the de Broglie wavelength of the particle is