A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by
(Where V is the potential difference between cathode and anode)
A
$${{{B^2}} \over {2V{E^2}}}$$
B
$${{2V{B^2}} \over {{E^2}}}$$
C
$${{2V{E^2}} \over {{B^2}}}$$
D
$${{{E^2}} \over {2V{B^2}}}$$
2
AIPMT 2010 Prelims
MCQ (Single Correct Answer)
+4
-1
The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work functions 5.01 eV, when ultraviolet light of 200 nm falls on it, must be
A
2.4 V
B
$$-$$ 1.2 V
C
$$-$$ 2.4 V
D
1.2 V
3
AIPMT 2009
MCQ (Single Correct Answer)
+4
-1
The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?
A
Curves (a) and (b) represent incident radiations of same frequency but of different intensities.
B
Curves (b) and (c) represent incident radiations of different frquencies and different intensities.
C
Curves (b) and (C) represent incident radiations of same frequency having same intensity.
D
Curves (a) and (b) represent incident radiations of different frequencies and different intensities
4
AIPMT 2009
MCQ (Single Correct Answer)
+4
-1
Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is
