1
JEE Main 2020 (Online) 9th January Morning Slot
+4
-1
A particle moving with kinetic energy E has de Broglie wavelength $$\lambda$$. If energy $$\Delta$$E is added to its energy, the wavelength become $$\lambda$$/2. Value of $$\Delta$$E, is :
A
E
B
3E
C
2E
D
4E
2
JEE Main 2020 (Online) 9th January Morning Slot
+4
-1
Radiation, with wavelength 6561 $$\mathop A\limits^o$$ falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3 × 10–4 T. If the radius of the largest circular path followed by the electrons is 10 mm, the work function of the metal is close to :
A
1.8eV
B
0.8eV
C
1.1eV
D
1.6eV
3
JEE Main 2020 (Online) 7th January Evening Slot
+4
-1
The activity of a radioactive sample falls from 700 s–1 to 500 s–1 in 30 minutes. Its half life is close to:
A
62 min
B
66 min
C
72 min
D
52 min
4
JEE Main 2020 (Online) 7th January Evening Slot
+4
-1
An electron (of mass m) and a photon have the same energy E in the range of a few eV. The ratio of the de-Broglie wavelength associated with the electron and the wavelength of the photon is (c = speed of light in vaccuum)
A
$${1 \over c}{\left( {{{2E} \over m}} \right)^{{1 \over 2}}}$$
B
$${1 \over c}{\left( {{E \over {2m}}} \right)^{{1 \over 2}}}$$
C
$${\left( {{E \over {2m}}} \right)^{{1 \over 2}}}$$
D
$$c{\left( {2mE} \right)^{{1 \over 2}}}$$
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
EXAM MAP
Joint Entrance Examination