1
NEET 2013
MCQ (Single Correct Answer)
+4
-1
A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?
A
The angular width of the central maximum will decrease.
B
The angular wifth of the central maximum will be unaffected.
C
Diffraction pattern is not observed on the screen in the case of electrons.
D
The angular width of the central maximum of the diffraction pattern will increase.
2
NEET 2013
MCQ (Single Correct Answer)
+4
-1
For photoelectric emission from certain metal the cutoff frequency is $$\upsilon $$. If radiation of frequency 2$$\upsilon $$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)
A
$$\sqrt {{{2h\upsilon } \over m}} $$
B
$$2\sqrt {{{h\upsilon } \over m}} $$
C
$$\sqrt {{{h\upsilon } \over {\left( {2m} \right)}}} $$
D
$$\sqrt {{{h\upsilon } \over m}} $$
3
NEET 2013
MCQ (Single Correct Answer)
+4
-1
The wavelength $$\lambda $$e of an electron and $$\lambda $$p of a photon of same energy E are related by
A
$${\lambda _p} \propto \sqrt {{\lambda _e}} $$
B
$${\lambda _p} \propto {1 \over {\sqrt {{\lambda _e}} }}$$
C
$${\lambda _p} \propto {\lambda _e}^2$$
D
$${\lambda _p} \propto {\lambda _e}$$
4
NEET 2013
MCQ (Single Correct Answer)
+4
-1
Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is
A
$${7 \over {29}}$$
B
$${9 \over {31}}$$
C
$${5 \over {27}}$$
D
$${3 \over {23}}$$
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