1
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
Hydrogen $$\left( {{}_1{H^1}} \right)$$, Deuterium $$\left( {{}_1{H^2}} \right)$$, singly ionised Helium $${\left( {{}_2H{e^4}} \right)^ + }$$ and doubly ionised lithium $${\left( {{}_3L{i^6}} \right)^{ + + }}$$ all have one electron around the nucleus. Consider an electron transition from $$n=2$$ to $$n=1.$$ If the wavelengths of emitted radiation are $${\lambda _1},{\lambda _2},{\lambda _3}$$ and $${\lambda _4}$$ respectively then approximately which one of the following is correct?
A
$$4{\lambda _1} = 2{\lambda _2} = 2{\lambda _3} = {\lambda _4}$$
B
$${\lambda _1} = 2{\lambda _2} = 2{\lambda _3} = {\lambda _4}$$
C
$${\lambda _1} = {\lambda _2} = 4{\lambda _3} = 9{\lambda _4}$$
D
$${\lambda _1} = 2{\lambda _2} = 3{\lambda _3} = 4{\lambda _4}$$
2
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
During the propagation of electromagnetic waves in a medium :
A
Electric energy density is double of the magnetic energy density.
B
Electric energy density is half of the magnetic energy density.
C
Electric energy density is equal to the magnetic energy density.
D
Both electric and magnetic energy of densities are zero.
3
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
Change Language
The current voltage relation of diode is given by $${\rm I} = \left( {{e^{100V/T}} - 1} \right)mA,$$ where the applied voltage $$V$$ is in volts and the temperature $$T$$ is in degree kelvin. If a student makes an error measuring $$ \pm 0.01\,V$$ while measuring the current of $$5$$ $$mA$$ at $$300$$ $$K,$$ what will be the error in the value of current on $$mA$$?
A
$$0.2$$ $$mA$$
B
$$0.02$$ $$mA$$
C
$$0.5$$ $$mA$$
D
$$0.05$$ $$mA$$
4
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
The radiation corresponding to $$3 \to 2$$ transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field $$3 \times {10^{ - 4}}\,T.$$ If the radius of the larger circular path followed by these electrons is $$10.0$$ $$mm$$, the work function of the metal is close to:
A
$$1.8$$ $$eV$$
B
$$1.1$$ $$eV$$
C
$$0.8$$ $$eV$$
D
$$1.6$$ $$eV$$
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