1
NEET 2021
MCQ (Single Correct Answer)
+4
-1
Change Language
An electromagnetic wave of wavelength '$$\lambda$$' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength $$\lambda$$d, then :
A
$$\lambda = \left( {{{2h} \over {mc}}} \right){\lambda _d}^2$$
B
$$\lambda = \left( {{{2m} \over {hc}}} \right){\lambda _d}^2$$
C
$${\lambda _d} = \left( {{{2mc} \over h}} \right){\lambda ^2}$$
D
$$\lambda = \left( {{{2mc} \over h}} \right){\lambda _d}^2$$
2
NEET 2021
MCQ (Single Correct Answer)
+4
-1
Change Language
A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since :
A
a large aperture contributes to the quality and visibility of the images.
B
a large area of the objective ensures better light gathering power.
C
a large aperture provides a better resolution.
D
All the above.
3
NEET 2021
MCQ (Single Correct Answer)
+4
-1
Change Language
Two charged spherical conductors of radius R1 and R2 are connected by a wire. Then the ratio of surface charge densities of the spheres ($$\sigma$$1 / $$\sigma$$2) is :
A
$${{R_1^2} \over {R_2^2}}$$
B
$${{R_1^{}} \over {R_2^{}}}$$
C
$${{R_2^{}} \over {R_1^{}}}$$
D
$$\sqrt {\left( {{{{R_1}} \over {{R_2}}}} \right)} $$
4
NEET 2021
MCQ (Single Correct Answer)
+4
-1
Change Language
For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B) respectively?
A
$$ - \widehat j + \widehat k, - \widehat j + \widehat k$$
B
$$ \widehat j + \widehat k, \widehat j + \widehat k$$
C
$$ - \widehat j + \widehat k, - \widehat j - \widehat k$$
D
$$\widehat j + \widehat k, - \widehat j - \widehat k$$
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