1
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
An EM wave is propagating in a medium with a velocity $$\overrightarrow v = v\widehat i$$. The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along
A
z direction
B
+z direction
C
–y direction
D
–x direction
2
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of
A
small focal length and large diameter
B
large focal length and small diameter
C
large focal length and large diameter
D
small focal length and small diameter
3
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
An electron of mass m with an initial velocity $$\overrightarrow v = {v_0}\widehat i$$ (v0 > 0) enters an electric field $$\overrightarrow E = - {\overrightarrow E _0}\widehat i$$ (E0 = constant > 0) at t = 0. If $$\lambda $$0 is its de-Broglie wavelength initially, then its de- Broglie wavelength at time t is
A
$${{{\lambda _0}} \over {\left( {1 + {{e{E_0}} \over {m{v_0}}}t} \right)}}$$
B
$${{\lambda _0}\left( {1 + {{e{E_0}} \over {m{v_0}}}t} \right)}$$
C
$$\lambda $$0t
D
$$\lambda $$0
4
NEET 2018
MCQ (Single Correct Answer)
+4
-1
Change Language
When the light of frequency 2$${\upsilon _0}$$ (where $${\upsilon _0}$$ is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v1 . When the frequency of the incident radiation is increased to 5$${\upsilon _0}$$ , the maximum velocity of electrons emitted from the same plate is v2 . The ratio of v1 to v2 is
A
1 : 2
B
1 : 4
C
4 : 1
D
2 : 1