## Dual Nature Of Radiation and Matter Quiz-9

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background.

Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced.

Q1. A photon in motion has a mass
•   c/hv
•  h/v
•  hv
•  hv/c2
Solution
E=hv=mc2⇒m=hv/c2

Q82.The intensity of X-rays from a coolidge tube is plotted against wavelength Î» as shown in figure. The minimum wavelength found is Î»c and the wavelength of KÎ± like is Î»K. As the accelerating voltage is increased
•  Î»k-Î»c increases
•  Î»k-Î»c decreases
•  Î»k increases
•  Î»k decreases
Solution
As accelerating voltage V across X-rays tube increase, the value of minimum wavelength of X-rays, Î»c=hc/eV; decreases ; so the separation between Î»k and Î»c increases.

Q83.  The mean free path of the electrons in a discharge tube is 20 cm. The length of the tube is 15 cm only. Then length of Crooke’s dark space is
•   5 cm
•  20 cm
•  15 cm
•  25 cm
Solution
The length of Crooke’s dark space will be equal to the length of tube ie,15cm

Q84. An X-ray tube with a copper target emits KÎ± line of wavelength 1.50 â„«. What should be the minimum voltage through which electrons are to be accelerated to produce this wavelength of X rays (h=6.63×10-34 J-s,c=3×108 m/s)
•  8280 V
•  828 V
•  82800 V
•  8.28 V
Solution

Q85.The anode voltage of a photocell is kept fixed. The wavelength Î» of the light falling on the cathode is gradually changed. The plate current 1 of the photocell varies as follows
•

•

•

•

Solution
On increasing wavelength of light of the photoelectric current decreases and at a certain wavelength (cut off) above which photoelectric current stops

Q86. When subjected to a transverse electric field, cathode rays move
• Along a hyperbolic path
•  Along a circular path
Solution
In an electric field, a force opposite to the direction of electric field acts on negatively charged particles (i.e. from lower potential to higher potential)

Q87.An electromagnetic radiation has an energy of 13.2 keV. Then the radiation belongs to the
•  Visible light
•  Ultraviolet
•  Infrared
•  X-ray
Solution

Q88. In an ionisation experiment it is found that a doubly ionised particle enters a magnetic field of 1 T and moves in a circular path of radius 1 m with a speed of 1.6×107 ms-1. The particle must be
•  C++
•  Be++
•  Li++
•  He++
Solution

Q89.The resistance of a discharge tube is d
•  Zero
•  Ohmic
•  Non-ohmic
•  Infinity
Solution
In discharge tube, the current is due to flow of positions ions and electrons. Moreover secondary emission of electrons is also possible. So, V –I curve is non-linear, hence its resistance is non-ohmic.

Q90. Electrons ejected from the surface of a metal, when light of certain frequency is incident on it, are stopped fully by a retarding potential of 3 V. Photoelectric effect in this metallic surface begins at a frequency 6×1014 s-1. The frequency of the incident light in s-1 is [Planck’s constant = 6.4×10-34) Js, charge on the electron = 1.6×10-19)C]
•  7.5×1013
•  13.5×1013
•  13.5×1013
• 7.5×1013
Solution

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